workspace: Update focus when a window is moved away from the current desktop

If a focussed window is to a new virtual desktop we need to update focus. It
does not make sense for focus to remain on a now-invisible window. This patch
re-uses the same path as when virtual desktop is changed.

BUG: 481574


(cherry picked from commit b96e6cf0b3)

Co-authored-by: David Edmundson <kde@davidedmundson.co.uk>

autotests/integration/kwinbindings_test.cpp

@@ -238,10 +238,17 @@ void KWinBindingsTest::testWindowToDesktop()
     invokeShortcut(desktop);
     QVERIFY(desktopsChangedSpy.wait());
     QCOMPARE(window->desktops(), QList<VirtualDesktop *>{desktops.at(desktop - 1)});
+
+    // window to Desktop does not change the current desktop, change it manually
+    VirtualDesktopManager::self()->setCurrent(desktops.at(desktop - 1));
+
     // back to desktop 1
     invokeShortcut(1);
     QVERIFY(desktopsChangedSpy.wait());
     QCOMPARE(window->desktops(), QList<VirtualDesktop *>{desktops.at(0)});
+
+    VirtualDesktopManager::self()->setCurrent(desktops.at(0));
+
     // invoke with one desktop too many
     invokeShortcut(desktop + 1);
     // that should fail

src/workspace.cpp

@@ -932,7 +932,7 @@ void Workspace::slotCurrentDesktopChanged(VirtualDesktop *oldDesktop, VirtualDes
     // Restore the focus on this desktop
     --block_focus;
 
-    activateWindowOnNewDesktop(newDesktop);
+    activateWindowOnDesktop(newDesktop);
     Q_EMIT currentDesktopChanged(oldDesktop, m_moveResizeWindow);
 }
 
@@ -985,7 +985,7 @@ void Workspace::updateWindowVisibilityOnDesktopChange(VirtualDesktop *newDesktop
     }
 }
 
-void Workspace::activateWindowOnNewDesktop(VirtualDesktop *desktop)
+void Workspace::activateWindowOnDesktop(VirtualDesktop *desktop)
 {
     Window *window = nullptr;
     if (options->focusPolicyIsReasonable()) {
@@ -1476,6 +1476,7 @@ void Workspace::sendWindowToDesktops(Window *window, const QList<VirtualDesktop
 {
     const QList<VirtualDesktop *> oldDesktops = window->desktops();
     const bool wasOnCurrent = window->isOnCurrentDesktop();
+    const bool wasActive = window->isActive();
     window->setDesktops(desktops);
     if (window->desktops() != desktops) { // No change or desktop forced
         return;
@@ -1489,7 +1490,13 @@ void Workspace::sendWindowToDesktops(Window *window, const QList<VirtualDesktop
             restackWindowUnderActive(window);
         }
     } else {
+
+        // raise the window on the desktop it has been added to
         raiseWindow(window);
+        // but set a new active window on the current desktop
+        if (wasActive) {
+            activateWindowOnDesktop(VirtualDesktopManager::self()->currentDesktop());
+        }
     }
 
     window->checkWorkspacePosition(QRect(), oldDesktops.isEmpty() ? nullptr : oldDesktops.last());

src/workspace.h

@@ -637,7 +637,7 @@ private:
 
     void closeActivePopup();
     void updateWindowVisibilityOnDesktopChange(VirtualDesktop *newDesktop);
-    void activateWindowOnNewDesktop(VirtualDesktop *desktop);
+    void activateWindowOnDesktop(VirtualDesktop *desktop);
     Window *findWindowToActivateOnDesktop(VirtualDesktop *desktop);
     void removeWindow(Window *window);
     QString getPlacementTrackerHash();