fix #333,restore previous functionality

--the only way I have found to show correct
tooltips is to hide and show the previews
window with some small delay, all the rest
workarounds do not work, they create different
issues

plasmoid/contents/ui/ToolTipInstance.qml

@@ -178,23 +178,12 @@ Column {
             // TODO: this causes XCB error message when being visible the first time
             property int winId: isWin && windows[flatIndex] != undefined ? windows[flatIndex] : 0
 
-            onWinIdChanged: {
-                if (winId !== previewThumb.prevWinId){
-                    previewThumb.visible = false;
-                    previewThumb.prevWinId = winId;
-                    previewThumb.visible = true;
-                }
-
-            }
-
             PlasmaCore.WindowThumbnail {
                 id: previewThumb
                 anchors.fill: parent
 
                 visible: !albumArtImage.visible && !thumbnailSourceItem.isMinimized
-                winId: prevWinId //thumbnailSourceItem.winId
-
-                property int prevWinId: 0
+                winId: thumbnailSourceItem.winId
 
                 ToolTipWindowMouseArea {
                     id: area2

plasmoid/contents/ui/main.qml

@@ -362,7 +362,7 @@ Item {
                 //console.log("preview show called: accepted...");
 
                 //used to initialize windows previews buffers from task to task
-                visible = true;
+                visible = false;
                 activeItem = taskItem;
                 toolTipDelegate.parentTask = taskItem;
 
@@ -372,10 +372,21 @@ Item {
                     signalSent = true;
                     //root.signalDraggingState(true);
                 }
+
+                showPreviewWinTimer.start();
             }
         }
     }
 
+    //! 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
+    Timer {
+        id: showPreviewWinTimer
+        interval: 50
+        onTriggered: windowsPreviewDlg.visible = true;
+    }
+
     /////Window Previews/////////
 
     TaskManager.TasksModel {