diff --git a/.arcconfig b/.arcconfig
new file mode 100644
--- /dev/null
+++ b/.arcconfig
@@ -0,0 +1,3 @@
+{
+  "phabricator.uri" : "https://phabricator.kde.org/"
+}
diff --git a/.gitignore b/.gitignore
--- a/.gitignore
+++ b/.gitignore
@@ -16,6 +16,6 @@
 Makefile
 avail
 random_seed
-/build*/
+/*build*/
 CMakeLists.txt.user*
 *.unc-backup*
diff --git a/app/formatdialog.cpp b/app/formatdialog.cpp
--- a/app/formatdialog.cpp
+++ b/app/formatdialog.cpp
@@ -227,7 +227,7 @@
     { nullptr, nullptr, 0, 0 }
 };
 
-static QString sLastFormat = QString::null;		// format last used, whether
+static QString sLastFormat;				// format last used, whether
 							// remembered or not
 
 FormatDialog::FormatDialog(QWidget *parent, ImageMetaInfo::ImageType type,
diff --git a/app/galleryhistory.cpp b/app/galleryhistory.cpp
--- a/app/galleryhistory.cpp
+++ b/app/galleryhistory.cpp
@@ -51,7 +51,7 @@
 // Data for display - what the user sees
 static QString entryName(const FileTreeBranch *branch, const QString &relPath)
 {
-    QString name = QString::null;
+    QString name;
 
     FileTreeView *view = static_cast<FileTreeView *>(branch->root()->treeWidget());
     if (view == nullptr) {
@@ -110,7 +110,7 @@
 
 void GalleryHistory::slotActivated(int idx)
 {
-    QString branchName = QString::null;
+    QString branchName;
 
     QString relPath = itemData(idx).toString();
     int ix = relPath.indexOf(GALLERY_PATH_SEP);     // is the separator present?
diff --git a/app/imgprintdialog.cpp b/app/imgprintdialog.cpp
--- a/app/imgprintdialog.cpp
+++ b/app/imgprintdialog.cpp
@@ -318,7 +318,7 @@
         return (i18n("A valid size must be specified for custom scaling. One or both of the specified dimensions is zero."));
     }
 
-    return (QString::null);				// no problems
+    return (QString());				// no problems
 }
 
 
diff --git a/app/imgsaver.h b/app/imgsaver.h
--- a/app/imgsaver.h
+++ b/app/imgsaver.h
@@ -101,7 +101,7 @@
     ImgSaver::ImageSaveStatus saveImage(const QImage *image,
                                         const QUrl &url,
                                         const ImageFormat &format,
-                                        const QString &subformat = QString::null);
+                                        const QString &subformat = QString());
 
     /**
      * Save an image.
@@ -200,7 +200,7 @@
      * this must be either 1, 8, 24 or 32.  The default is for no colour
      * conversion.
      *
-     * @return The file name as saved, or @c QString::null if there was
+     * @return The file name as saved, or @c QString() if there was
      *         an error.
      **/
     static QString tempSaveImage(const KookaImage *img, const ImageFormat &format, int colors = -1);
diff --git a/app/imgsaver.cpp b/app/imgsaver.cpp
--- a/app/imgsaver.cpp
+++ b/app/imgsaver.cpp
@@ -172,14 +172,16 @@
 {
     if (image == nullptr) return (ImgSaver::SaveStatusParam);
 
-    if (!mSaveFormat.isValid()) {			// see if have this already
+    if (!mSaveFormat.isValid())				// see if have this already
+    {
         // if not, get from image now
         //qDebug() << "format not resolved yet";
         ImgSaver::ImageSaveStatus stat = getFilenameAndFormat(ImageMetaInfo::findImageType(image));
         if (stat != ImgSaver::SaveStatusOk) return (stat);
     }
 
-    if (!mSaveUrl.isValid() || !mSaveFormat.isValid()) { // must have these now
+    if (!mSaveUrl.isValid() || !mSaveFormat.isValid())	// must have these now
+    {
         //qDebug() << "format not resolved!";
         return (ImgSaver::SaveStatusParam);
     }
@@ -244,7 +246,7 @@
  **/
 QString ImgSaver::createFilename()
 {
-    if (!m_saveDirectory.isLocalFile()) return (QString::null);
+    if (!m_saveDirectory.isLocalFile()) return (QString());
     // TODO: allow non-local files
     QDir files(m_saveDirectory.path(), "kscan_[0-9][0-9][0-9][0-9].*");
     QStringList l(files.entryList());
@@ -360,43 +362,43 @@
 QString ImgSaver::findSubFormat(const ImageFormat &format)
 {
     //qDebug() << "for" << format;
-    return (QString::null);             // no subformats currently used
+    return (QString());					// no subformats currently used
 }
 
 QString ImgSaver::errorString(ImgSaver::ImageSaveStatus status) const
 {
     QString re;
     switch (status) {
     case ImgSaver::SaveStatusOk:
-        re = i18n("Save OK");                           break;
+        re = i18n("Save OK");							break;
     case ImgSaver::SaveStatusPermission:
-        re = i18n("Permission denied");                     break;
-    case ImgSaver::SaveStatusBadFilename:           // never used
-        re = i18n("Bad file name");                     break;
-    case ImgSaver::SaveStatusNoSpace:           // never used
-        re = i18n("No space left on device");                   break;
+        re = i18n("Permission denied");						break;
+    case ImgSaver::SaveStatusBadFilename:		// never used
+        re = i18n("Bad file name");						break;
+    case ImgSaver::SaveStatusNoSpace:			// never used
+        re = i18n("No space left on device");					break;
     case ImgSaver::SaveStatusFormatNoWrite:
-        re = i18n("Cannot write image format '%1'", mLastFormat.constData());   break;
+        re = i18n("Cannot write image format '%1'", mLastFormat.constData());	break;
     case ImgSaver::SaveStatusProtocol:
-        re = i18n("Cannot write using protocol '%1'", mLastUrl.scheme()); break;
+        re = i18n("Cannot write using protocol '%1'", mLastUrl.scheme());	break;
     case ImgSaver::SaveStatusCanceled:
-        re = i18n("User cancelled saving");                 break;
+        re = i18n("User cancelled saving");					break;
     case ImgSaver::SaveStatusMkdir:
-        re = i18n("Cannot create directory");                   break;
+        re = i18n("Cannot create directory");					break;
     case ImgSaver::SaveStatusFailed:
-        re = i18n("Save failed");                       break;
+        re = i18n("Save failed");						break;
     case ImgSaver::SaveStatusParam:
-        re = i18n("Bad parameter");                     break;
+        re = i18n("Bad parameter");						break;
     default:
-        re = i18n("Unknown status %1", status);                 break;
+        re = i18n("Unknown status %1", status);					break;
     }
     return (re);
 }
 
 
 bool copyRenameImage(bool isCopying, const QUrl &fromUrl, const QUrl &toUrl, bool askExt, QWidget *overWidget)
 {
-    QString errorString = QString::null;
+    QString errorString;
 
     /* Check if the provided filename has a extension */
     QString extFrom = extension(fromUrl);
@@ -465,7 +467,7 @@
         return (false);
     }
 
-    return (true);                  // file operation succeeded
+    return (true);					// file operation succeeded
 }
 
 bool ImgSaver::renameImage(const QUrl &fromUrl, const QUrl &toUrl, bool askExt, QWidget *overWidget)
diff --git a/app/kookaimage.cpp b/app/kookaimage.cpp
--- a/app/kookaimage.cpp
+++ b/app/kookaimage.cpp
@@ -126,7 +126,7 @@
             const QString fileName = url.adjusted(QUrl::RemoveFragment).toLocalFile();
             qDebug() << "subimage" << subno << "from" << fileName;
             loadTiffDir(fileName, subno);		// load TIFF subimage
-            return (QString::null);
+            return (QString());
         }
 
     }
@@ -179,7 +179,7 @@
 
     m_url = url;					// record image source
     m_fileBound = true;					// note loaded from file
-    return (QString::null);				// loaded OK
+    return (QString());				// loaded OK
 }
 
 
@@ -258,7 +258,7 @@
 #else
     return (i18n("TIFF not supported"));
 #endif							// HAVE_TIFF
-    return (QString::null);				// TIFF read succeeded
+    return (QString());				// TIFF read succeeded
 }
 
 
diff --git a/app/kookapref.cpp b/app/kookapref.cpp
--- a/app/kookapref.cpp
+++ b/app/kookapref.cpp
@@ -99,9 +99,9 @@
     item->setHeader(header);
     item->setIcon(QIcon::fromTheme(icon));
 
-    int idx = mPages.count();               // index of new item
+    int idx = mPages.count();				// index of new item
     mPages.append(item);
-    return (idx);                   // index of item added
+    return (idx);					// index of item added
 }
 
 void KookaPref::slotSaveSettings()
@@ -137,7 +137,7 @@
 
 // Support for the gallery location - moved here from Previewer class in libkscan
 
-QString KookaPref::sGalleryRoot = QString::null;    // global resolved location
+QString KookaPref::sGalleryRoot;			// global resolved location
 
 // The static variable above ensures that the user is only asked
 // at most once in an application run.
@@ -211,7 +211,7 @@
     if (galleryName.isEmpty())
     {
         qWarning() << "Gallery name not configured";
-        return (QString::null);
+        return (QString());
     }
 
     QString oldpath = QStandardPaths::locate(QStandardPaths::AppDataLocation, "ScanImages", QStandardPaths::LocateDirectory);
@@ -257,7 +257,7 @@
                                                 "<nl/>then you may do so by simply copying or moving the files.",
                                                 newpath, oldpath),
                                          i18n("New Gallery Created"),
-                                         QString::null,
+                                         QString(),
                                          KMessageBox::Notify | KMessageBox::AllowLink);
             }
         } else {					// no, don't create
diff --git a/app/kookaview.cpp b/app/kookaview.cpp
--- a/app/kookaview.cpp
+++ b/app/kookaview.cpp
@@ -489,7 +489,7 @@
                                      KScanDevice::statusMessage(stat),
                                      selDevice.constData());
 
-                int tryAgain = KMessageBox::warningContinueCancel(mMainWindow, msg, QString::null,
+                int tryAgain = KMessageBox::warningContinueCancel(mMainWindow, msg, QString(),
                                KGuiItem("Retry"));
                 if (tryAgain == KMessageBox::Cancel) {
                     break;
@@ -563,7 +563,7 @@
                                                       "you need to specify the device to use. "
                                                       "Use the <interface>Add Scan Device</interface> option to enter the backend name and parameters, "
                                                       "or see that dialog for more information."),
-                                               QString::null,
+                                               QString(),
                                                KGuiItem(i18n("Add Scan Device..."))) != KMessageBox::Continue)
         {
             return ("");
diff --git a/app/scangallery.h b/app/scangallery.h
--- a/app/scangallery.h
+++ b/app/scangallery.h
@@ -127,7 +127,7 @@
 
 private:
     void loadImageForItem(FileTreeViewItem *item);
-    FileTreeBranch *openRoot(const QUrl &root, const QString &title = QString::null);
+    FileTreeBranch *openRoot(const QUrl &root, const QString &title = QString());
 
     FileTreeViewItem *findItemByUrl(const QUrl &url, FileTreeBranch *branch = nullptr);
     QUrl itemDirectory(const FileTreeViewItem *item) const;
diff --git a/app/scangallery.cpp b/app/scangallery.cpp
--- a/app/scangallery.cpp
+++ b/app/scangallery.cpp
@@ -472,7 +472,7 @@
                 if (isSubImage)				// subimages don't show size
                 {
                     item->setIcon(0, QIcon::fromTheme("edit-copy"));
-                    item->setText(1, QString::null);
+                    item->setText(1, QString());
                 }
                 else
                 {
@@ -683,7 +683,7 @@
     {
         item = findItemInBranch(branches().at(0), relPath);
     }
-    if (item == nullptr) return;				// not found in branch
+    if (item == nullptr) return;			// not found in branch
 
     scrollToItem(item);
     setCurrentItem(item);
@@ -699,7 +699,7 @@
 #ifdef DEBUG_LOADING
     qDebug() << "loading" << item->url();
 #endif // DEBUG_LOADING
-    QString ret = QString::null;			// no error so far
+    QString ret;					// no error so far
 
     ImageFormat format = getImgFormat(item);		// check for valid image format
     if (!format.isValid())
@@ -815,13 +815,13 @@
         return (nullptr);    // is a directory
     }
 
-    KookaImage *img = imageForItem(curr);       // see if already loaded
-    if (img == nullptr) {              // no, try to do that
+    KookaImage *img = imageForItem(curr);		// see if already loaded
+    if (img == nullptr) {				// no, try to do that
         if (!loadOnDemand) {
-            return (nullptr);    // not loaded, and don't want to
+            return (nullptr);				// not loaded, and don't want to
         }
-        slotItemActivated(curr);            // select/load this image
-        img = imageForItem(curr);           // and get image for it
+        slotItemActivated(curr);			// select/load this image
+        img = imageForItem(curr);			// and get image for it
     }
 
     return (img);
@@ -833,11 +833,11 @@
     QString result = "";
 
     const FileTreeViewItem *curr = highlightedFileTreeViewItem();
-    if (curr==nullptr) return (QString::null);
+    if (curr==nullptr) return (QString());
 
     bool isLocal = false;
     const QUrl u = curr->fileItem()->mostLocalUrl(isLocal);
-    if (!isLocal) return (QString::null);
+    if (!isLocal) return (QString());
     return (u.toLocalFile());
 }
 
@@ -850,12 +850,12 @@
         //qDebug() << "type" << info->getImageType();
     }
 
-    delete mSaver; mSaver = nullptr;           // recreate with clean info
+    delete mSaver; mSaver = nullptr;			// recreate with clean info
 
     // Resolve where to save the new image when it arrives
     FileTreeViewItem *curr = highlightedFileTreeViewItem();
-    if (curr == nullptr) {             // into root if nothing is selected
-        FileTreeBranch *branch = branches().at(0);  // there should be at least one
+    if (curr == nullptr) {				// into root if nothing is selected
+        FileTreeBranch *branch = branches().at(0);	// there should be at least one
         if (branch != nullptr) {
             // if user has created this????
             curr = findItemInBranch(branch, i18n("Incoming/"));
@@ -870,21 +870,21 @@
         curr->setSelected(true);
     }
 
-    mSavedTo = curr;                    // note for selecting later
+    mSavedTo = curr;					// note for selecting later
 
     // Create the ImgSaver to use later
-    QUrl dir(itemDirectory(curr));          // where new image will go
-    mSaver = new ImgSaver(dir);             // create saver to use later
+    QUrl dir(itemDirectory(curr));			// where new image will go
+    mSaver = new ImgSaver(dir);				// create saver to use later
 
-    if (info != nullptr) {             // have image information,
-        // tell saver about it
+    if (info != nullptr) {				// have image information,
+							// tell saver about it
         ImgSaver::ImageSaveStatus stat = mSaver->setImageInfo(info);
         if (stat == ImgSaver::SaveStatusCanceled) {
             return (false);
         }
     }
 
-    return (true);                  // all ready to save
+    return (true);					// all ready to save
 }
 
 QUrl ScanGallery::saveURL() const
@@ -907,27 +907,27 @@
     //qDebug() << "size" << img->size() << "depth" << img->depth();
 
     if (mSaver == nullptr) {
-        prepareToSave(nullptr);    // if not done already
+        prepareToSave(nullptr);				// if not done already
     }
     if (mSaver == nullptr) {
-        return;    // should never happen
+        return;						// should never happen
     }
 
     ImgSaver::ImageSaveStatus isstat = mSaver->saveImage(img);
     // try to save the image
-    QUrl lurl = mSaver->lastURL();          // record where it ended up
+    QUrl lurl = mSaver->lastURL();			// record where it ended up
 
-    if (isstat != ImgSaver::SaveStatusOk &&     // image saving failed
+    if (isstat != ImgSaver::SaveStatusOk &&		// image saving failed
             isstat != ImgSaver::SaveStatusCanceled) {   // user cancelled, just ignore
         KMessageBox::error(this, xi18nc("@info", "Could not save the image<nl/><filename>%2</filename><nl/>%1",
                                         mSaver->errorString(isstat),
                                         lurl.url(QUrl::PreferLocalFile)),
                            i18n("Image Save Error"));
     }
 
-    delete mSaver; mSaver = nullptr;           // now finished with this
+    delete mSaver; mSaver = nullptr;			// now finished with this
 
-    if (isstat == ImgSaver::SaveStatusOk) {     // image was saved OK,
+    if (isstat == ImgSaver::SaveStatusOk) {		// image was saved OK,
         // select the new image
         slotSetNextUrlToSelect(lurl);
         m_nextUrlToShow = lurl;
@@ -1097,19 +1097,19 @@
         return;
     }
 
-    if (curr->isDir()) {                // is a directory
+    if (curr->isDir()) {				// is a directory
         for (int i = 0; i < curr->childCount(); ++i) {
             FileTreeViewItem *child = static_cast<FileTreeViewItem *>(curr->child(i));
-            slotUnloadItem(child);          // recursively unload contents
+            slotUnloadItem(child);			// recursively unload contents
         }
-    } else {                    // is a file/image
+    } else {						// is a file/image
         const KookaImage *image = imageForItem(curr);
         if (image == nullptr) {
-            return;    // ok, nothing to unload
+            return;					// ok, nothing to unload
         }
 
-        if (image->subImagesCount() > 0) {      // image with subimages
-            while (curr->childCount() > 0) {    // recursively unload subimages
+        if (image->subImagesCount() > 0) {		// image with subimages
+            while (curr->childCount() > 0) {		// recursively unload subimages
                 FileTreeViewItem *child = static_cast<FileTreeViewItem *>(curr->takeChild(0));
                 slotUnloadItem(child);
                 delete child;
@@ -1119,7 +1119,7 @@
         emit unloadImage(image);
         delete image;
 
-        curr->setClientData(nullptr);          // clear image from item
+        curr->setClientData(nullptr);			// clear image from item
         slotDecorate(curr);
     }
 }
@@ -1142,8 +1142,8 @@
         return;
     }
 
-    QUrl urlToDel = curr->url();            // item to be deleted
-    bool isDir = curr->isDir();             // deleting a folder?
+    QUrl urlToDel = curr->url();			// item to be deleted
+    bool isDir = curr->isDir();				// deleting a folder?
     QTreeWidgetItem *nextToSelect = curr->treeWidget()->itemBelow(curr);
     // select this afterwards
     QString s;
@@ -1180,8 +1180,8 @@
         return;
     }
 
-    updateParent(curr);                 // update parent folder count
-    if (isDir) {                    // remove from the name combo
+    updateParent(curr);					// update parent folder count
+    if (isDir) {					// remove from the name combo
         emit galleryDirectoryRemoved(curr->branch(), itemDirectoryRelative(curr));
     }
 
diff --git a/app/scanparamsdialog.cpp b/app/scanparamsdialog.cpp
--- a/app/scanparamsdialog.cpp
+++ b/app/scanparamsdialog.cpp
@@ -179,12 +179,12 @@
 
 void ScanParamsDialog::slotSave()
 {
-    QString name = QString::null;
+    QString name;
     QListWidgetItem *item = paramsList->currentItem();
     if (item != nullptr) name = item->text();
     //qDebug() << "selected set" << name;
 
-    QString newdesc = QString::null;
+    QString newdesc;
     if (sets.contains(name)) {
         newdesc = sets[name];
     } else {
diff --git a/app/statusbarmanager.cpp b/app/statusbarmanager.cpp
--- a/app/statusbarmanager.cpp
+++ b/app/statusbarmanager.cpp
@@ -120,7 +120,7 @@
 
 void StatusBarManager::clearStatus(StatusBarManager::Item item)
 {
-    setStatus(QString::null, item);
+    setStatus(QString(), item);
 }
 
 
diff --git a/libdialogutil/recentsaver.h b/libdialogutil/recentsaver.h
--- a/libdialogutil/recentsaver.h
+++ b/libdialogutil/recentsaver.h
@@ -92,7 +92,7 @@
      * @return The resolved URL, or a null URL if there is no saved
      * history.
      **/
-    QUrl recentUrl(const QString &suggestedName = QString::null);
+    QUrl recentUrl(const QString &suggestedName = QString());
 
     /**
      * Resolve the saved recent location (if there is one) and a suggested
@@ -104,7 +104,7 @@
      * @return The resolved file path, or a null string if there is no
      * saved history.
      **/
-    QString recentPath(const QString &suggestedName = QString::null);
+    QString recentPath(const QString &suggestedName = QString());
 
     /**
      * Save the location selected by the file dialogue as a new recent location.
diff --git a/libfiletree/filetreebranch.cpp b/libfiletree/filetreebranch.cpp
--- a/libfiletree/filetreebranch.cpp
+++ b/libfiletree/filetreebranch.cpp
@@ -307,7 +307,7 @@
 //
 //    QUrl url = fi.url();
 //    //qDebug() << "for" << url;
-//    url.setFileName(QString::null);
+//    url.setFileName(QString());
 //    return (findItemByUrl(url));
 //}
 
diff --git a/libkookascan/autoselectbar.cpp b/libkookascan/autoselectbar.cpp
--- a/libkookascan/autoselectbar.cpp
+++ b/libkookascan/autoselectbar.cpp
@@ -67,7 +67,7 @@
 
     // Threshold setting slider/spinbox
     int maxThresh = item->maxValue().toInt();
-    mThresholdSlider = new KScanSlider(nullptr, QString::null, 0, maxThresh);
+    mThresholdSlider = new KScanSlider(nullptr, QString(), 0, maxThresh);
     mThresholdSlider->setValue(initialValue);
     mThresholdSlider->setToolTip(item->toolTip());
     l->setBuddy(mThresholdSlider);
diff --git a/libkookascan/autoselectdialog.cpp b/libkookascan/autoselectdialog.cpp
--- a/libkookascan/autoselectdialog.cpp
+++ b/libkookascan/autoselectdialog.cpp
@@ -68,7 +68,7 @@
     int maxVal = item->maxValue().toInt();
     int minVal = item->minValue().toInt();
 
-    mMarginSlider = new KScanSlider(nullptr, QString::null, minVal, maxVal, true, defaultVal);
+    mMarginSlider = new KScanSlider(nullptr, QString(), minVal, maxVal, true, defaultVal);
     mMarginSlider->setValue(defaultVal);
     mMarginSlider->setToolTip(item->toolTip());
     connect(mMarginSlider, SIGNAL(settingChanged(int)), SLOT(slotControlChanged()));
@@ -93,7 +93,7 @@
     maxVal = item->maxValue().toInt();
     minVal = item->minValue().toInt();
 
-    mDustsizeSlider = new KScanSlider(nullptr, QString::null, minVal, maxVal, true, defaultVal);
+    mDustsizeSlider = new KScanSlider(nullptr, QString(), minVal, maxVal, true, defaultVal);
     mDustsizeSlider->setValue(defaultVal);
     mDustsizeSlider->setToolTip(item->toolTip());
     connect(mDustsizeSlider, SIGNAL(settingChanged(int)), SLOT(slotControlChanged()));
diff --git a/libkookascan/kscancontrols.h b/libkookascan/kscancontrols.h
--- a/libkookascan/kscancontrols.h
+++ b/libkookascan/kscancontrols.h
@@ -94,7 +94,7 @@
     /**
      * Get the control's current text value.
      *
-     * @return the text value, or @c QString::null for a @c Number
+     * @return the text value, or @c QString() for a @c Number
      * or @c Group control.
      */
     virtual QString text() const;
diff --git a/libkookascan/kscancontrols.cpp b/libkookascan/kscancontrols.cpp
--- a/libkookascan/kscancontrols.cpp
+++ b/libkookascan/kscancontrols.cpp
@@ -71,7 +71,7 @@
 
 QString KScanControl::text() const
 {
-    return (QString::null);
+    return (QString());
 }
 void KScanControl::setText(const QString &text)     {}
 
@@ -257,7 +257,7 @@
 
 QString KScanCheckbox::label() const
 {
-    return (QString::null);
+    return (QString());
 }
 
 //  KScanCombo - combo box with list of options
@@ -332,7 +332,7 @@
 
 QString KScanCombo::textAt(int i) const
 {
-    return (i == -1 ? QString::null : mCombo->itemData(i).toString());
+    return (i == -1 ? QString() : mCombo->itemData(i).toString());
 }
 
 int KScanCombo::count() const
@@ -392,7 +392,7 @@
 
 QString KScanGroup::label() const
 {
-    return (QString::null);
+    return (QString());
 }
 
 //  KScanPushButton - action button
@@ -409,5 +409,5 @@
 
 QString KScanPushButton::label() const
 {
-    return (QString::null);
+    return (QString());
 }
diff --git a/libkookascan/kscandevice.h b/libkookascan/kscandevice.h
--- a/libkookascan/kscandevice.h
+++ b/libkookascan/kscandevice.h
@@ -175,7 +175,7 @@
      * If this is a null or empty string, a real scan is performed.
      * @return The status of the operation
      **/
-    KScanDevice::Status acquireScan(const QString &filename = QString::null);
+    KScanDevice::Status acquireScan(const QString &filename = QString());
 
     /**
      * Get the standard file name for saving the preview image for the
diff --git a/libkookascan/kscanoptset.h b/libkookascan/kscanoptset.h
--- a/libkookascan/kscanoptset.h
+++ b/libkookascan/kscanoptset.h
@@ -120,7 +120,7 @@
      * optSet.saveConfig(saneDevice->scannerBackendName(), setDesc);
      * @endcode
      **/
-    void saveConfig(const QByteArray &scannerName, const QString &desc = QString::null) const;
+    void saveConfig(const QByteArray &scannerName, const QString &desc = QString()) const;
 
     /**
      * Load an option set from the global scanner configuration file.
diff --git a/libkookascan/kscanoptset.cpp b/libkookascan/kscanoptset.cpp
--- a/libkookascan/kscanoptset.cpp
+++ b/libkookascan/kscanoptset.cpp
@@ -57,7 +57,7 @@
 static QString setNameFromGroup(const QString &grpName)
 {
     QString prefix = ScanSettings::self()->saveSetDescItem()->group();
-    if (!grpName.startsWith(prefix)) return (QString::null);
+    if (!grpName.startsWith(prefix)) return (QString());
     return (grpName.mid(prefix.length()+1));
 }
 
diff --git a/libkookascan/scanparams.cpp b/libkookascan/scanparams.cpp
--- a/libkookascan/scanparams.cpp
+++ b/libkookascan/scanparams.cpp
@@ -157,7 +157,7 @@
 {
     addGroup(nullptr);                 // hide last if present
 
-    mLayout->addWidget(new QLabel(QString::null, this), mNextRow, 0, 1, -1, Qt::AlignTop);
+    mLayout->addWidget(new QLabel(QString(), this), mNextRow, 0, 1, -1, Qt::AlignTop);
     mLayout->setRowStretch(mNextRow, 9);
 
     return (mNextRow > 0);
@@ -269,7 +269,7 @@
     lay->addWidget(pb, 5, 1, Qt::AlignRight);
 
     /* Initialise the progress dialog */
-    mProgressDialog = new QProgressDialog(QString::null, i18n("Stop"), 0, 100, nullptr);
+    mProgressDialog = new QProgressDialog(QString(), i18n("Stop"), 0, 100, nullptr);
     mProgressDialog->setModal(true);
     mProgressDialog->setAutoClose(true);
     mProgressDialog->setAutoReset(true);
@@ -279,7 +279,7 @@
     // appears to show itself after the default 'minimumDuration' (= 4 seconds),
     // even despite the previous and no 'value' being set.
     mProgressDialog->reset();
-    setScanDestination(QString::null);			// reset destination display
+    setScanDestination(QString());			// reset destination display
 
     connect(mProgressDialog, &QProgressDialog::canceled, mSaneDevice, &KScanDevice::slotStopScanning);
     connect(mSaneDevice, &KScanDevice::sigScanProgress, this, &ScanParams::slotScanProgress);
@@ -362,7 +362,7 @@
 
         // Separator line after these.  Using a KScanGroup with a null text,
         // so that it looks the same as any real group separators following.
-        frame->addGroup(new KScanGroup(frame, QString::null));
+        frame->addGroup(new KScanGroup(frame, QString()));
     }
 
     // Mode setting
@@ -449,7 +449,7 @@
     frame->addRow(l, mAreaSelect, nullptr, Qt::AlignTop);
 
     // Insert another beautification line
-    frame->addGroup(new KScanGroup(frame, QString::null));
+    frame->addGroup(new KScanGroup(frame, QString()));
 
     // Source selection
     mSourceSelect = mSaneDevice->getGuiElement(SANE_NAME_SCAN_SOURCE, frame);
@@ -680,7 +680,7 @@
     //qDebug() << "new source" << sel_source << "ADF" << adf;
 
     /* set the selected Document source, the behavior is stored in a membervar */
-    mSourceSelect->set(sel_source.toLatin1());      // TODO: FIX in ScanSourceDialog, then here
+    mSourceSelect->set(sel_source.toLatin1());		// TODO: FIX in ScanSourceDialog, then here
     mSourceSelect->apply();
     mSourceSelect->reload();
     mSourceSelect->redrawWidget();
@@ -712,13 +712,13 @@
 {
     //qDebug() << "scan mode=" << mScanMode;
 
-    setScanDestination(QString::null);          // reset progress display
+    setScanDestination(QString());			// reset progress display
 
     // Check compatibility of scan settings
     int format;
     int depth;
     mSaneDevice->getCurrentFormat(&format, &depth);
-    if (depth == 1 && format != SANE_FRAME_GRAY) {  // 1-bit scan depth in colour?
+    if (depth == 1 && format != SANE_FRAME_GRAY) {	// 1-bit scan depth in colour?
         KMessageBox::sorry(this, i18n("1-bit depth scan cannot be done in color"));
         return (KScanDevice::ParamError);
     } else if (depth == 16) {
@@ -803,8 +803,8 @@
         greyPreview->get(&gp);
     }
 
-    setMaximalScanSize();               // always preview at maximal size
-    mAreaSelect->selectCustomSize(QRect());     // reset selector to reflect that
+    setMaximalScanSize();				// always preview at maximal size
+    mAreaSelect->selectCustomSize(QRect());		// reset selector to reflect that
 
     stat = mSaneDevice->acquirePreview(gp);
     if (stat != KScanDevice::Ok) {
@@ -823,7 +823,7 @@
 
     //qDebug() << "scan mode=" << mScanMode << "virtfile" << virtfile;
 
-    if (mScanMode != ScanParams::VirtualScannerMode) { // acquire via SANE
+    if (mScanMode != ScanParams::VirtualScannerMode) {	// acquire via SANE
 #if 0
 // TODO: port/update
         if (adf == ADF_OFF) {
@@ -874,7 +874,7 @@
 
 void ScanParams::slotEditCustGamma()
 {
-    KGammaTable gt;                 // start with default values
+    KGammaTable gt;					// start with default values
 
     // Get the current gamma table from either the combined gamma table
     // option, or any one of the colour channel gamma tables.
@@ -912,9 +912,9 @@
     bool reload = false;
 
     KScanOption *so = mSaneDevice->getOption(SANE_NAME_CUSTOM_GAMMA);
-    if (so != nullptr) {               // do we have a gamma switch?
+    if (so != nullptr) {				// do we have a gamma switch?
         int cg = 0;
-        if (so->get(&cg) && !cg) {          // yes, see if already on
+        if (so->get(&cg) && !cg) {			// yes, see if already on
             // if not, set it on now
             //qDebug() << "Setting gamma switch on";
             so->set(true);
@@ -929,7 +929,7 @@
     reload |= setGammaTableTo(SANE_NAME_GAMMA_VECTOR_B, gt);
 
     if (reload) {
-        mSaneDevice->reloadAllOptions();    // reload is needed
+        mSaneDevice->reloadAllOptions();		// reload is needed
     }
 }
 
@@ -1013,7 +1013,7 @@
     double min1, max1;
     double min2, max2;
 
-    if (!rect.isValid()) {              // set full scan area
+    if (!rect.isValid()) {				// set full scan area
         tl_x->getRange(&min1, &max1); tl_x->set(min1);
         br_x->getRange(&min1, &max1); br_x->set(max1);
         tl_y->getRange(&min2, &max2); tl_y->set(min2);
@@ -1098,10 +1098,10 @@
     //qDebug() << "X/Y resolution" << x_res << y_res;
 
     if (y_res == 0) {
-        y_res = x_res;    // use X res if Y unavailable
+        y_res = x_res;					// use X res if Y unavailable
     }
     if (x_res == 0) {
-        x_res = y_res;    // unlikely, but orthogonal
+        x_res = y_res;					// unlikely, but orthogonal
     }
 
     if (x_res == 0 && y_res == 0) {
@@ -1121,8 +1121,8 @@
 
     qDebug() << "format" << format << "depth" << depth << "-> strips " << strips;
 
-    if (strips == 1 && depth == 1) {        // bitmap scan
-        emit scanModeChanged(0);            // 8 pixels per byte
+    if (strips == 1 && depth == 1) {			// bitmap scan
+        emit scanModeChanged(0);			// 8 pixels per byte
     } else {
         // bytes per pixel
         emit scanModeChanged(strips * (depth == 16 ? 2 : 1));
diff --git a/libkookascan/scansourcedialog.cpp b/libkookascan/scansourcedialog.cpp
--- a/libkookascan/scansourcedialog.cpp
+++ b/libkookascan/scansourcedialog.cpp
@@ -77,7 +77,7 @@
                            "Note that you may see more sources than actually exist"), vbox);
 
     /* Combo Box for sources */
-    d->sources = new KScanCombo(vbox, QString::null);
+    d->sources = new KScanCombo(vbox, QString());
     d->sources->setList(list);
     connect(d->sources, SIGNAL(activated(int)), SLOT(slotChangeSource(int)));
 
diff --git a/plugins/ocr/abstractocrdialogue.h b/plugins/ocr/abstractocrdialogue.h
--- a/plugins/ocr/abstractocrdialogue.h
+++ b/plugins/ocr/abstractocrdialogue.h
@@ -92,7 +92,7 @@
 
     QProgressBar *progressBar() const;
 
-    void ocrShowInfo(const QString &binary, const QString &version = QString::null);
+    void ocrShowInfo(const QString &binary, const QString &version = QString());
     void ocrShowVersion(const QString &version);
 
     QWidget *addExtraSetupWidget(QWidget *wid = nullptr, bool stretchBefore = false);
diff --git a/plugins/ocr/abstractocrdialogue.cpp b/plugins/ocr/abstractocrdialogue.cpp
--- a/plugins/ocr/abstractocrdialogue.cpp
+++ b/plugins/ocr/abstractocrdialogue.cpp
@@ -445,7 +445,7 @@
 {
     //qDebug() << "pixmap" << newPix.size();
     if (m_previewPix != nullptr) {
-        m_previewPix->setText(QString::null);
+        m_previewPix->setText(QString());
         m_previewPix->setPixmap(newPix);
     }
 }
diff --git a/plugins/ocr/abstractocrengine.h b/plugins/ocr/abstractocrengine.h
--- a/plugins/ocr/abstractocrengine.h
+++ b/plugins/ocr/abstractocrengine.h
@@ -124,16 +124,16 @@
      * this must be either 1, 8, 24 or 32.  The default is for no colour
      * conversion.
      *
-     * @return The file name as saved, or @c QString::null if there was
+     * @return The file name as saved, or @c QString() if there was
      *         an error.
      **/
     QString tempSaveImage(const KookaImage *img, const ImageFormat &format, int colors = -1);
 
     /**
      * Get a name to use for a temporary file.
      *
      * @param suffix File name suffix, no leading '.' is required
-     * @return The temporary file name, or @c QString::null if the file could not be created
+     * @return The temporary file name, or @c QString() if the file could not be created
      *
      * @note The temporary file is created and is left in place under the returned name,
      * but is not opened.  Its name should be saved and eventually returned in the
diff --git a/plugins/ocr/abstractocrengine.cpp b/plugins/ocr/abstractocrengine.cpp
--- a/plugins/ocr/abstractocrengine.cpp
+++ b/plugins/ocr/abstractocrengine.cpp
@@ -250,7 +250,7 @@
                                        i18n("OCR Temporary Files"),
                                        KStandardGuiItem::del(),
                                        KStandardGuiItem::close(),
-                                       QString::null,
+                                       QString(),
                                        KMessageBox::AllowLink)==KMessageBox::Yes) retain = false;
     }
 
@@ -411,7 +411,7 @@
     {
         qDebug() << "error creating temporary file" << protoName;
         setErrorText(xi18nc("@info", "Cannot create temporary file <filename>%1</filename>", protoName));
-        return (QString::null);
+        return (QString());
     }
 
     QString tmpName = QFile::encodeName(tmpFile.fileName());
@@ -422,7 +422,7 @@
 
 QString AbstractOcrEngine::tempSaveImage(const KookaImage *img, const ImageFormat &format, int colors)
 {
-    if (img==nullptr) return (QString::null);		// no image to save
+    if (img==nullptr) return (QString());		// no image to save
 
     QString tmpName = tempFileName(format.extension(), "imagetemp");
     const KookaImage *tmpImg = nullptr;
@@ -445,7 +445,7 @@
             break;
 
 default:    qWarning() << "bad colour depth" << colors;
-            return (QString::null);
+            return (QString());
         }
 
         tmpImg = new KookaImage(img->convertToFormat(newfmt));
diff --git a/plugins/ocr/gocr/ocrgocrdialog.cpp b/plugins/ocr/gocr/ocrgocrdialog.cpp
--- a/plugins/ocr/gocr/ocrgocrdialog.cpp
+++ b/plugins/ocr/gocr/ocrgocrdialog.cpp
@@ -51,7 +51,7 @@
 
 OcrGocrDialog::OcrGocrDialog(AbstractOcrEngine *plugin, QWidget *pnt)
     : AbstractOcrDialogue(plugin, pnt),
-      m_ocrCmd(QString::null)
+      m_ocrCmd(QString())
 {
 }
 
@@ -68,7 +68,7 @@
     QLabel *l = new QLabel(ski->label(), w);
     gl->addWidget(l, 0, 0);
 
-    sliderGrayLevel = new KScanSlider(w, QString::null, 0, 254, true, 160);
+    sliderGrayLevel = new KScanSlider(w, QString(), 0, 254, true, 160);
     int numdefault = KookaSettings::ocrGocrGrayLevel();
     sliderGrayLevel->setValue(numdefault);
     sliderGrayLevel->setToolTip(ski->toolTip());
@@ -79,7 +79,7 @@
     Q_ASSERT(ski!=nullptr);
     l = new QLabel(ski->label(), w);
     gl->addWidget(l, 1, 0);
-    sliderDustSize = new KScanSlider(w, QString::null, 0, 60, true, 10);
+    sliderDustSize = new KScanSlider(w, QString(), 0, 60, true, 10);
     numdefault = KookaSettings::ocrGocrDustSize();
     sliderDustSize->setValue(numdefault);
     sliderDustSize->setToolTip(ski->toolTip());
@@ -90,7 +90,7 @@
     Q_ASSERT(ski!=nullptr);
     l = new QLabel(ski->label(), w);
     gl->addWidget(l, 2, 0);
-    sliderSpace = new KScanSlider(w, QString::null, 0, 60, true, 0);
+    sliderSpace = new KScanSlider(w, QString(), 0, 60, true, 0);
     numdefault = KookaSettings::ocrGocrSpaceWidth();
     sliderSpace->setValue(numdefault);
     sliderSpace->setToolTip(ski->toolTip());
diff --git a/plugins/ocr/gocr/ocrgocrengine.cpp b/plugins/ocr/gocr/ocrgocrengine.cpp
--- a/plugins/ocr/gocr/ocrgocrengine.cpp
+++ b/plugins/ocr/gocr/ocrgocrengine.cpp
@@ -69,8 +69,8 @@
     : AbstractOcrEngine(pnt, "OcrGocrEngine")
 {
     m_tempDir = nullptr;
-    m_inputFile = QString::null;			// input image file
-    m_resultFile = QString::null;			// OCR result text file
+    m_inputFile = QString();			// input image file
+    m_resultFile = QString();			// OCR result text file
 }
 
 
diff --git a/plugins/ocr/kadmos/ocrkadmosdialog.cpp b/plugins/ocr/kadmos/ocrkadmosdialog.cpp
--- a/plugins/ocr/kadmos/ocrkadmosdialog.cpp
+++ b/plugins/ocr/kadmos/ocrkadmosdialog.cpp
@@ -288,7 +288,7 @@
         slotFontChanged(0);    // Load machine print font language list
     }
 
-    ocrShowInfo(QString::null);
+    ocrShowInfo(QString());
     return err;
 }
 
diff --git a/plugins/ocr/kadmos/ocrkadmosengine.cpp b/plugins/ocr/kadmos/ocrkadmosengine.cpp
--- a/plugins/ocr/kadmos/ocrkadmosengine.cpp
+++ b/plugins/ocr/kadmos/ocrkadmosengine.cpp
@@ -47,7 +47,7 @@
 OcrKadmosEngine::OcrKadmosEngine(QWidget *parent)
     : OcrEngine(parent)
 {
-    m_tmpFile = QString::null;
+    m_tmpFile = QString();
 }
 
 OcrKadmosEngine::~OcrKadmosEngine()
@@ -211,7 +211,7 @@
 #ifdef USE_KADMOS_FILEOP
     if (!m_tmpFile.isNull()) {
         result << m_tmpFile;
-        m_tmpFile = QString::null;
+        m_tmpFile = QString();
     }
 #endif
 
diff --git a/plugins/ocr/ocrad/ocrocraddialog.cpp b/plugins/ocr/ocrad/ocrocraddialog.cpp
--- a/plugins/ocr/ocrad/ocrocraddialog.cpp
+++ b/plugins/ocr/ocrad/ocrocraddialog.cpp
@@ -58,9 +58,9 @@
       m_setupWidget(nullptr),
       m_orfUrlRequester(nullptr),
       m_layoutMode(0),
-      m_ocrCmd(QString::null),
+      m_ocrCmd(QString()),
       m_versionNum(0),
-      m_versionStr(QString::null)
+      m_versionStr(QString())
 {
 }
 
@@ -223,15 +223,15 @@
     KookaSettings::setOcrOcradLayoutDetection(m_layoutMode->currentIndex());
 
     int ix = m_characterSet->currentIndex();
-    QString value = (m_characterSet->itemData(ix).toBool() ? m_characterSet->currentText() : QString::null);
+    QString value = (m_characterSet->itemData(ix).toBool() ? m_characterSet->currentText() : QString());
     KookaSettings::setOcrOcradCharset(value);
 
     ix = m_filter->currentIndex();
-    value = (m_filter->itemData(ix).toBool() ? m_filter->currentText() : QString::null);
+    value = (m_filter->itemData(ix).toBool() ? m_filter->currentText() : QString());
     KookaSettings::setOcrOcradFilter(value);
 
     ix = m_transform->currentIndex();
-    value = (m_transform->itemData(ix).toBool() ? m_transform->currentText() : QString::null);
+    value = (m_transform->itemData(ix).toBool() ? m_transform->currentText() : QString());
     KookaSettings::setOcrOcradTransform(value);
 
     KookaSettings::setOcrOcradInvert(m_invert->isChecked());
@@ -252,7 +252,7 @@
     if (m_orfUrlRequester != nullptr) {
         return (m_orfUrlRequester->url().url());
     } else {
-        return (QString::null);
+        return (QString());
     }
 }
 
diff --git a/plugins/ocr/ocrad/ocrocradengine.cpp b/plugins/ocr/ocrad/ocrocradengine.cpp
--- a/plugins/ocr/ocrad/ocrocradengine.cpp
+++ b/plugins/ocr/ocrad/ocrocradengine.cpp
@@ -58,8 +58,8 @@
 OcrOcradEngine::OcrOcradEngine(QObject *pnt, const QVariantList &args)
     : AbstractOcrEngine(pnt, "OcrOcradEngine")
 {
-    m_ocrImagePBM = QString::null;
-    m_tempOrfName = QString::null;
+    m_ocrImagePBM = QString();
+    m_tempOrfName = QString();
     ocradVersion = 0;
 }
 
@@ -274,7 +274,7 @@
     startResultDocument();
 
     while (!stream.atEnd()) {
-        line = stream.readLine().trimmed();     // line of text excluding '\n'
+        line = stream.readLine().trimmed();		// line of text excluding '\n'
 
         if (line.startsWith("#")) {
             continue;    // ignore comments
@@ -284,17 +284,17 @@
             //qDebug() << "# Line" << line;
         }
         if (line.startsWith("source file ")) {
-            continue;    // source file name, ignore
-        } else if (line.startsWith("total blocks ")) { // total count of blocks,
-            // must be first line
+            continue;					// source file name, ignore
+        } else if (line.startsWith("total blocks ")) {	// total count of blocks,
+							// must be first line
             blockCnt = line.mid(13).toInt();
             qDebug() << "Block count (V<10)" << blockCnt;
         } else if (line.startsWith("total text blocks ")) {
             blockCnt = line.mid(18).toInt();
             qDebug() << "Block count (V>10)" << blockCnt;
         } else if (line.startsWith("block ") || line.startsWith("text block ")) {
-            // start of text block
-            // matching "block 1 0 0 560 792"
+							// start of text block
+							// matching "block 1 0 0 560 792"
             if (rx1.indexIn(line) == -1) {
                 //qDebug() << "Failed to match 'block' line" << line;
                 continue;
@@ -304,9 +304,9 @@
             blockRect.setRect(rx1.cap(2).toInt(), rx1.cap(3).toInt(),
                               rx1.cap(4).toInt(), rx1.cap(5).toInt());
             //qDebug() << "Current block" << currBlock << "rect" << blockRect;
-        } else if (line.startsWith("lines ")) { // lines in this block
+        } else if (line.startsWith("lines ")) {		// lines in this block
             //qDebug() << "Block line count" << line.mid(6).toInt();
-        } else if (line.startsWith("line ")) {  // start of text line
+        } else if (line.startsWith("line ")) {		// start of text line
             startLine();
 
             if (rx2.indexIn(line) == -1) {
@@ -345,8 +345,8 @@
                 }
 
                 int altCount = rx3.cap(1).toInt();
-                if (altCount == 0) {        // no alternatives,
-                    // undecipherable character
+                if (altCount == 0) {			// no alternatives,
+							// undecipherable character
                     if (verboseDebug()) {
                         //qDebug() << "Undecipherable character in 'char' line" << charLine;
                     }
@@ -374,33 +374,33 @@
                     }
                 }
 
-                if (detectedChar == ' ') {      // space terminates the word
-                    if (ocradVersion < 10) {    // offset is relative to block
+                if (detectedChar == ' ') {		// space terminates the word
+                    if (ocradVersion < 10) {		// offset is relative to block
                         wordRect.translate(blockRect.x(), blockRect.y());
                     }
 
                     OcrWordData wd;
                     wd.setProperty(OcrWordData::Rectangle, wordRect);
                     addWord(word, wd);
 
-                    word = QString::null;       // reset for next time
+                    word = QString();			// reset for next time
                     wordRect = QRect();
                 } else {
-                    word.append(detectedChar);    // append char to word
+                    word.append(detectedChar);		// append char to word
                 }
-            }                       // end of text line loop
+            }						// end of text line loop
             ++lineNo;
 
-            if (!word.isEmpty()) {          // last word in line
-                if (ocradVersion < 10) {        // offset is relative to block
+            if (!word.isEmpty()) {			// last word in line
+                if (ocradVersion < 10) {		// offset is relative to block
                     wordRect.translate(blockRect.x(), blockRect.y());
                 }
 
                 OcrWordData wd;
                 wd.setProperty(OcrWordData::Rectangle, wordRect);
                 addWord(word, wd);
 
-                word = QString::null;           // reset for next time
+                word = QString();			// reset for next time
                 wordRect = QRect();
             }
 
@@ -410,11 +410,11 @@
         }
     }
 
-    file.close();                   // finished with ORF file
+    file.close();					// finished with ORF file
     finishResultDocument();
     qDebug() << "Finished analysing ORF";
 
-    return (QString::null);             // no error detected
+    return (QString());					// no error detected
 }