taskswitcher: fixes for opening phase

components/mobileshell/qml/taskswitcher/Task.qml

@@ -221,15 +221,20 @@ Item {
                     // app icon (behind window preview in-case it doesn't load)
                     TaskIcon {
                         // decrease the opacity faster
-                        opacity: delegate.opacity
+                        opacity: pipeWireLoader.item && pipeWireLoader.item.uuid ? 0 : delegate.opacity
                         anchors.centerIn: parent
                     }
 
                     // attempt to load window preview
                     Loader {
                         id: pipeWireLoader
+                        active: taskSwitcher.visible || taskSwitcher.tasksModel.taskReorderingEnabled
                         anchors.fill: parent
                         source: Qt.resolvedUrl("./Thumbnail.qml")
+                        
+                        asynchronous: true
+                        
+                        onLoaded: this.item.refresh()
                     }
                     
                     // darken effect

components/mobileshell/qml/taskswitcher/Thumbnail.qml

@@ -11,19 +11,25 @@ import QtQuick.Window 2.2
 import org.kde.taskmanager 0.1 as TaskManager
 
 TaskManager.PipeWireSourceItem {
-    visible: Window.visibility !== Window.Hidden
+    visible: false
     nodeId: waylandItem.nodeId
+    
+    // Visible only if casting has begun
+    onNodeIdChanged: {
+        visible = true;
+    }
+    
+    readonly property string uuid: waylandItem.uuid
 
-    onVisibleChanged: {
-        if (visible) {
-            if (model.WinIdList) {
-                waylandItem.uuid = model.WinIdList[0];
-            }
+    function refresh() {
+        if (model.WinIdList) {
+            waylandItem.uuid = model.WinIdList[0];
         }
     }
 
     TaskManager.ScreencastingRequest {
         id: waylandItem
+        uuid: ""
     }
 }