Index: kate/kateapp.h
===================================================================
--- kate/kateapp.h
+++ kate/kateapp.h
@@ -190,6 +190,13 @@
      * @return success
      */
     bool openUrl(const QUrl &url, const QString &encoding, bool isTempFile);
+    
+    /**
+     * checks if the current instance is in a given activity
+     * @param activity activity to check
+     * @return true if the window is in the given activity, false otherwise
+     */
+    bool isOnActivity(QString activity);
 
     KTextEditor::Document *openDocUrl(const QUrl &url, const QString &encoding, bool isTempFile);
 
Index: kate/kateapp.cpp
===================================================================
--- kate/kateapp.cpp
+++ kate/kateapp.cpp
@@ -29,6 +29,7 @@
 #include <KLocalizedString>
 #include <KConfigGui>
 #include <KConfigGroup>
+#include <KWindowInfo>
 
 #include <QCommandLineParser>
 #include <QFileInfo>
@@ -272,6 +273,20 @@
     return openDocUrl(url, encoding, isTempFile);
 }
 
+bool KateApp::isOnActivity(QString activity)
+{
+    for (const auto& window : this->m_mainWindows) {
+        WId id = window->winId();
+        
+        KWindowInfo info = KWindowInfo(id, 0, NET::WM2Activities);
+        
+        if (info.activities().contains(activity))
+            return true;
+    }
+    
+    return false;
+}
+
 KTextEditor::Document *KateApp::openDocUrl(const QUrl &url, const QString &encoding, bool isTempFile)
 {
     KateMainWindow *mainWindow = activeKateMainWindow();
Index: kate/kateappadaptor.h
===================================================================
--- kate/kateappadaptor.h
+++ kate/kateappadaptor.h
@@ -47,6 +47,13 @@
      * @return success
      */
     bool openUrl(QString url, QString encoding);
+        
+    /**
+     * checks if the Kate instance is in the specified activity
+     * @param activity activity to check
+     * @return true if it is in the specified activity, false otherwise
+     */
+    bool isOnActivity(QString activity);
 
     /**
      * open a file with given url and encoding
Index: kate/kateappadaptor.cpp
===================================================================
--- kate/kateappadaptor.cpp
+++ kate/kateappadaptor.cpp
@@ -59,6 +59,10 @@
     return m_app->openUrl(QUrl(url), encoding, isTempFile);
 }
 
+bool KateAppAdaptor::isOnActivity(QString activity) {
+    return m_app->isOnActivity(activity);
+}
+
 //-----------
 QString KateAppAdaptor::tokenOpenUrl(QString url, QString encoding)
 {
Index: kate/main.cpp
===================================================================
--- kate/main.cpp
+++ kate/main.cpp
@@ -282,11 +282,47 @@
         if (!fillinRunningKateAppInstances(&mapSessionRii)) {
             return 1;
         }
+        
+        QString currentActivity;
+        QDBusMessage m = QDBusMessage::createMethodCall(
+                                        QStringLiteral("org.kde.ActivityManager"),
+                                        QStringLiteral("/ActivityManager/Activities"), QStringLiteral("org.kde.ActivityManager.Activities"), QStringLiteral("CurrentActivity"));
+        QDBusMessage res = QDBusConnection::sessionBus().call(m);
+        QList<QVariant> answer = res.arguments();
+        if (answer.size() == 1) {
+            currentActivity = answer.at(0).toString();
+        }
 
         QStringList kateServices;
         for (KateRunningInstanceMap::const_iterator it = mapSessionRii.constBegin(); it != mapSessionRii.constEnd(); ++it) {
-            kateServices << (*it)->serviceName;
+            QString serviceName = (*it)->serviceName;
+            
+            if (currentActivity.length() != 0) {
+                QDBusMessage m = QDBusMessage::createMethodCall(serviceName,
+                                        QStringLiteral("/MainApplication"), QStringLiteral("org.kde.Kate.Application"), QStringLiteral("isOnActivity"));
+                
+                QList<QVariant> dbargs;
+
+                // convert to an url
+                dbargs.append(currentActivity);
+                m.setArguments(dbargs);
+
+                QDBusMessage res = QDBusConnection::sessionBus().call(m);
+                QList<QVariant> answer = res.arguments();
+                if (answer.size() == 1) {
+                    bool canBeUsed = answer.at(0).toBool();
+                    
+                    // If the Kate instace is in a specific activity, add it to 
+                    // the list of candidate reusable services
+                    if (canBeUsed) {
+                        kateServices << serviceName;
+                    }
+                }
+            } else {
+                kateServices << serviceName;
+            }
         }
+        
         QString serviceName;
 
         QString start_session;
@@ -322,7 +358,7 @@
                 }
             }
         }
-
+        
         // prefer the Kate instance running on the current virtual desktop
         bool foundRunningService = false;
         if ((!force_new) && (serviceName.isEmpty())) {