DesktopSwitch: show unsupported widget if backend does not have switch

capability

Author: gfgit

panel/backends/lxqttaskbartypes.h

@@ -14,7 +14,8 @@ enum class LXQtTaskBarBackendAction
     MaximizeHorizontally,
     Minimize,
     RollUp,
-    FullScreen
+    FullScreen,
+    DesktopSwitch
 };
 
 enum class LXQtTaskBarWindowProperty

panel/backends/xcb/lxqttaskbarbackend_x11.cpp

@@ -202,6 +202,9 @@ bool LXQtTaskbarX11Backend::supportsAction(WId windowId, LXQtTaskBarBackendActio
         x11Action = NET::ActionFullScreen;
         break;
 
+    case LXQtTaskBarBackendAction::DesktopSwitch:
+        return true;
+
     default:
         return false;
     }

plugin-desktopswitch/desktopswitch.cpp

@@ -318,11 +318,12 @@ void DesktopSwitchWidget::wheelEvent(QWheelEvent *e)
 
 ILXQtPanelPlugin *DesktopSwitchPluginLibrary::instance(const ILXQtPanelPluginStartupInfo &startupInfo) const
 {
-    return new DesktopSwitch{startupInfo};
+    LXQtPanelApplication *a = reinterpret_cast<LXQtPanelApplication*>(qApp);
+    auto wmBackend = a ? a->getWMBackend() : nullptr;
+    if(!wmBackend || !wmBackend->supportsAction(0, LXQtTaskBarBackendAction::DesktopSwitch))
+        return new DesktopSwitchUnsupported{startupInfo};
 
-    //TODO: detect dummy backend and show unsupported message?
-    // Or instead remove it and make just a message box at application start
-    //return new DesktopSwitchUnsupported{startupInfo};
+    return new DesktopSwitch{startupInfo};
 }
 
 DesktopSwitchUnsupported::DesktopSwitchUnsupported(const ILXQtPanelPluginStartupInfo &startupInfo)