Delay performWindowOperation to next event cycle in UserActionsMenu

In case that the window operation results in destroying the window
decoration we need to have the menu closed before the deco gets
destroyed. Otherwise Qt crashes.

libkdecorations/kdecoration.h

@@ -1219,5 +1219,6 @@ inline int KDecoration::height() const
 /** @} */
 
 Q_DECLARE_OPERATORS_FOR_FLAGS(KDecoration::QuickTileMode)
+Q_DECLARE_METATYPE(KDecorationDefines::WindowOperation)
 
 #endif

useractions.cpp

@@ -770,7 +770,13 @@ void UserActionsMenu::slotWindowOperation(QAction *action)
     };
     if (!type.isEmpty())
         helperDialog(type, c);
-    Workspace::self()->performWindowOperation(c.data(), op);
+    // need to delay performing the window operation as we need to have the
+    // user actions menu closed before we destroy the decoration. Otherwise Qt crashes
+    qRegisterMetaType<KDecorationDefines::WindowOperation>();
+    QMetaObject::invokeMethod(workspace(), "performWindowOperation",
+                              Qt::QueuedConnection,
+                              Q_ARG(KWin::Client*, c.data()),
+                              Q_ARG(KDecorationDefines::WindowOperation, op));
 }
 
 void UserActionsMenu::slotSendToDesktop(QAction *action)

workspace.h

@@ -233,8 +233,6 @@ public:
     void updateOnAllDesktopsOfTransients(Client*);
     void checkTransients(xcb_window_t w);
 
-    void performWindowOperation(Client* c, WindowOperation op);
-
     void storeSession(KConfig* config, SMSavePhase phase);
     void storeClient(KConfigGroup &cg, int num, Client *c);
     void storeSubSession(const QString &name, QSet<QByteArray> sessionIds);
@@ -302,6 +300,7 @@ public:
     bool compositing() const;
 
 public Q_SLOTS:
+    void performWindowOperation(KWin::Client* c, KDecorationDefines::WindowOperation op);
     // Keybindings
     //void slotSwitchToWindow( int );
     void slotWindowToDesktop();