fix a crash when changing layouts/old sessions

--when changing layouts/old sessions from the Latte Tasks
Context menu, Latte was crashing very often. Add the switching
code into a Timer to make its execution asynchronoushly

app/globalsettings.cpp

@@ -107,11 +107,18 @@ void GlobalSettings::showWidgetsExplorer()
 
 void GlobalSettings::enableAltSession(bool enabled)
 {
-    if (enabled) {
-        m_corona->loadLatteLayout(QString(i18n("Alternative")));
-    } else {
-        m_corona->loadLatteLayout(QString(i18n("My Layout")));
-    }
+    //! this code must be called asynchronously because it is called
+    //! also from qml (Tasks plasmoid). This change fixes a very important
+    //! crash when switching sessions through the Tasks plasmoid Context menu
+    //! Latte was unstable and was crashing very often during changing
+    //! sessions
+    QTimer::singleShot(200, [this, enabled]() {
+        if (enabled) {
+            m_corona->loadLatteLayout(QString(i18n("Alternative")));
+        } else {
+            m_corona->loadLatteLayout(QString(i18n("My Layout")));
+        }
+    });
 }
 
 bool GlobalSettings::exposeAltSession() const

plasmoid/package/contents/ui/ContextMenu.qml

@@ -34,6 +34,8 @@ import "../code/activitiesTools.js" as ActivitiesTools
 PlasmaComponents.ContextMenu {
     id: menu
 
+    property bool changingLayout: false
+
     property QtObject mpris2Source
     property QtObject backend
 
@@ -264,13 +266,15 @@ PlasmaComponents.ContextMenu {
 
 
     Component.onDestruction: {
-        windowsPreviewDlg.contextMenu = false;
-        root.contextMenu = null;
-        backend.ungrabMouse(visualParent);
-        root.signalActionsBlockHiding(-1);
-        //root.signalDraggingState(false);
-        root.disableRestoreZoom = false;
-        checkListHovered.startDuration(100);
+        if (!changingLayout) {
+            windowsPreviewDlg.contextMenu = false;
+            root.contextMenu = null;
+            backend.ungrabMouse(visualParent);
+            root.signalActionsBlockHiding(-1);
+            //root.signalDraggingState(false);
+            root.disableRestoreZoom = false;
+            checkListHovered.startDuration(100);
+        }
     }
 
     /// Sub Items
@@ -800,6 +804,7 @@ PlasmaComponents.ContextMenu {
         onClicked: {
             //fix a crash that when going to Alternative Session through Context Menu,
             //animations are played during the destruction and because of that Latte.IconItem is crashing
+            menu.changingLayout = true;
             root.disableRestoreZoom = false;
             root.clearZoom();
             if (latteDock)

plasmoid/package/contents/ui/main.qml

@@ -495,6 +495,10 @@ Item {
         //this is the animation time needed in order for tasks to restore their zoom first
         interval: 7 * (root.durationTime * units.shortDuration)
         onTriggered: {
+            if (root.contextMenu) {
+                root.contextMenu.destroy();
+                root.contextMenu = null;
+            }
             if (root.altSessionAction)
                 root.altSessionAction.trigger();
         }