diff --git a/libtaskmanager/taskmanagerrulesrc b/libtaskmanager/taskmanagerrulesrc
--- a/libtaskmanager/taskmanagerrulesrc
+++ b/libtaskmanager/taskmanagerrulesrc
@@ -17,7 +17,7 @@
 MatchCommandLineFirst=VirtualBox
 
 [Rewrite Rules][google-chrome][1]
-Property=ClassName
+Property=ClassNameFixed a bug when switching wallpapers
 Identifier=DesktopEntryName
 Match=(?<=crx_)(?'match'[a-z]+)
 Target=chrome-%1-default
diff --git a/libtaskmanager/xwindowtasksmodel.cpp b/libtaskmanager/xwindowtasksmodel.cpp
--- a/libtaskmanager/xwindowtasksmodel.cpp
+++ b/libtaskmanager/xwindowtasksmodel.cpp
@@ -38,6 +38,7 @@
 
 #include <QBuffer>
 #include <QDir>
+#include <QDebug>
 #include <QIcon>
 #include <QFile>
 #include <QRegularExpression>
@@ -515,12 +516,14 @@
         if (!classClass.isEmpty() && matchCommandLineFirst.contains(classClass)) {
             triedPid = true;
             services = servicesFromPid(pid);
+            qDebug() << "a" << services;
         }
 
         // Try to match using className also.
-        if (!className.isEmpty() && matchCommandLineFirst.contains("::"+className)) {
+        if (services.empty() && !className.isEmpty() && matchCommandLineFirst.contains("::"+className)) {
             triedPid = true;
             services = servicesFromPid(pid);
+            qDebug() << "b" << services;
         }
 
         // If the user has manually set a mapping, respect this first...
@@ -606,6 +609,7 @@
             // To match other docks (docky, unity, etc.) attempt to match on DesktopEntryName first ...
             if (services.empty()) {
                 services = KServiceTypeTrader::self()->query(QStringLiteral("Application"), QStringLiteral("exist Exec and ('%1' =~ DesktopEntryName)").arg(classClass));
+                qDebug() << classClass << services;
             }
 
             // Try StartupWMClass.
@@ -619,6 +623,8 @@
             }
         }
 
+        qDebug() << "c" << services;
+
         // Ok, absolute *last* chance, try matching via pid (but only if we have not already tried this!) ...
         if (services.empty() && !triedPid) {
             services = servicesFromPid(pid);
@@ -768,6 +774,8 @@
     KSysGuard::Process *proc = procs.getProcess(pid);
     QString cmdline = proc ? proc->command().simplified() : QString(); // proc->command has a trailing space???
 
+    qDebug() << cmdline;
+
     if (cmdline.isEmpty()) {
         return services;
     }
@@ -779,7 +787,9 @@
         // Could not find with complete commandline, so strip out path part...
         int slash = cmdline.lastIndexOf('/', firstSpace);
         if (slash > 0) {
-            services = KServiceTypeTrader::self()->query(QStringLiteral("Application"), QStringLiteral("exist Exec and ('%1' =~ Exec)").arg(cmdline.mid(slash + 1)));
+            qDebug() << cmdline.mid(slash + 1);
+            services = KServiceTypeTrader::self()->query(QStringLiteral("Application"), QStringLiteral("exist Exec and ('VirtualBox' =~ Exec)"));
+            qDebug() << services;
         }
     }
 
@@ -790,7 +800,7 @@
 
         int slash = cmdline.lastIndexOf('/');
         if (slash > 0) {
-            services = KServiceTypeTrader::self()->query(QStringLiteral("Application"), QStringLiteral("exist Exec and ('%1' =~ Exec)").arg(cmdline.mid(slash + 1)));
+            services = KServiceTypeTrader::self()->query(QStringLiteral("Application"), QStringLiteral("exist Exec and ('%1' =~ Exec)").arg(cmdline.mid(slash + 1) + " %u"));
         }
     }
 
diff --git a/plasma-windowed/main.cpp b/plasma-windowed/main.cpp
--- a/plasma-windowed/main.cpp
+++ b/plasma-windowed/main.cpp
@@ -19,6 +19,9 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>
  */
 
+#define QT_QML_DEBUG
+#include <QtQuick>
+
 #include <QApplication>
 #include <qcommandlineparser.h>
 #include <qcommandlineoption.h>