[wayland] - fix previews crash

-- disable the use of PlasmaCore.WindowThumbnail
under Wayland in order to fix a crash that was
appearing after a while when the user was using
previews

BUG: 392865

plasmoid/package/contents/ui/ToolTipInstance.qml

@@ -198,23 +198,27 @@ Column {
             // TODO: this causes XCB error message when being visible the first time
             property int winId: isWin && windows[flatIndex] != undefined ? windows[flatIndex] : 0
 
-            PlasmaCore.WindowThumbnail {
-                id: previewThumb
+
+            Loader{
+                id:previewThumbX11Loader
                 anchors.fill: parent
-
+                active: !Latte.WindowSystem.isPlatformWayland
                 visible: !albumArtImage.visible && !thumbnailSourceItem.isMinimized
-                winId: thumbnailSourceItem.winId
 
-                ToolTipWindowMouseArea {
-                    id: area2
-
-                    anchors.fill: Latte.WindowSystem.isPlatformWayland ? parent : previewThumb
-                    rootTask: parentTask
-                    modelIndex: submodelIndex
+                sourceComponent: PlasmaCore.WindowThumbnail {
                     winId: thumbnailSourceItem.winId
                 }
             }
 
+            ToolTipWindowMouseArea {
+                id: area2
+
+                anchors.fill: Latte.WindowSystem.isPlatformWayland ? parent : previewThumbX11Loader
+                rootTask: parentTask
+                modelIndex: submodelIndex
+                winId: thumbnailSourceItem.winId
+            }
+
             Image {
                 id: albumArtImage
                 // also Image.Loading to prevent loading thumbnails just because the album art takes a split second to load
@@ -243,7 +247,8 @@ Column {
                 source: icon
                 animated: false
                 usesPlasmaTheme: false
-                visible: thumbnailSourceItem.isMinimized && !albumArtImage.visible
+                visible: (thumbnailSourceItem.isMinimized && !albumArtImage.visible) //X11 case
+                         || (!previewThumbX11Loader.active && !albumArtImage.visible) //Wayland case
 
                 ToolTipWindowMouseArea {
                     id: area4

plasmoid/package/contents/ui/main.qml

@@ -302,7 +302,7 @@ Item {
         target: latteDock
         onDockIsHiddenChanged:{
             if (latteDock.dockIsHidden) {
-                windowsPreviewDlg.hide();
+                windowsPreviewDlg.hide("3.3");
             }
         }
 
@@ -484,7 +484,7 @@ Item {
         }
 
         function hide(debug){
-            //console.log("on hide event called: "+debug);
+            //console.log("on hide previews event called: "+debug);
 
             if (latteDock && signalSent) {
                 //it is used to unblock dock hiding
@@ -523,7 +523,9 @@ Item {
                 }
 
                 //used to initialize windows previews buffers from task to task
-                visible = false;
+                if (!Latte.WindowSystem.isPlatformWayland) {
+                    visible = false;
+                }
                 activeItem = taskItem;
                 toolTipDelegate.parentTask = taskItem;
 
@@ -534,14 +536,18 @@ Item {
                     //root.signalDraggingState(true);
                 }
 
-                showPreviewWinTimer.start();
+                if (!Latte.WindowSystem.isPlatformWayland) {
+                    showPreviewWinTimer.start();
+                } else {
+                    visible = true;
+                }
             }
         }
     }
 
     //! I cant find another way to fix the issue with window thumbnails
     //! there are many cases that not correct previews are shown are
-    //! no previews in cases that they should
+    //! no previews in cases that they should (X11 related)
     Timer {
         id: showPreviewWinTimer
         interval: 50