make sure KFileDialog does not leave the SolarMutex released

Change-Id: I806bf5fe1cd1871de499ceeeadf36de539e9d637

vcl/unx/kde4/KDE4FilePicker.cxx

@@ -256,19 +256,17 @@ sal_Int16 SAL_CALL KDE4FilePicker::execute()
     _dialog->setFilter(_filter);
     _dialog->filterWidget()->setEditable(false);
 
-    // At this point, SolarMutex is held. Opening the KDE file dialog here
-    // can lead to QClipboard asking for clipboard contents. If LO core
-    // is the owner of the clipboard content, this will block for 5 seconds
-    // and timeout, since the clipboard thread will not be able to acquire
-    // SolarMutex and thus won't be able to respond. If the event loops
+    // KFileDialog intergration requires using event loop with QClipboard.
+    // Opening the KDE file dialog here can lead to QClipboard
+    // asking for clipboard contents. If LO core is the owner of the clipboard
+    // content, without event loop use this will block for 5 seconds and timeout,
+    // since the clipboard thread will not be able to acquire SolarMutex
+    // and thus won't be able to respond. If the event loops
     // are properly integrated and QClipboard can use a nested event loop
-    // (see the KDE VCL plug), then this won't happen, but otherwise
-    // simply release the SolarMutex here. The KDE file dialog does not
-    // call back to the core, so this should be safe (and if it does,
-    // SolarMutex will need to be re-acquired).
-    long mutexrelease = 0;
-    if( !qApp->clipboard()->property( "useEventLoopWhenWaiting" ).toBool())
-        mutexrelease = Application::ReleaseSolarMutex();
+    // (see the KDE VCL plug), then this won't happen.
+    // We cannot simply release SolarMutex here, because the event loop started
+    // by the file dialog would also call back to LO code.
+    assert( qApp->clipboard()->property( "useEventLoopWhenWaiting" ).toBool() == true );
     //block and wait for user input
     int result = _dialog->exec();
     // HACK: KFileDialog uses KConfig("kdeglobals") for saving some settings
@@ -276,8 +274,6 @@ sal_Int16 SAL_CALL KDE4FilePicker::execute()
     // (which is probably a KDE bug), so force reading the new configuration,
     // otherwise the next opening of the dialog would use the old settings.
     KGlobal::config()->reparseConfiguration();
-    if( !qApp->clipboard()->property( "useEventLoopWhenWaiting" ).toBool())
-        Application::AcquireSolarMutex( mutexrelease );
     if( result == KFileDialog::Accepted)
         return ExecutableDialogResults::OK;