Add a Toplevel *Workspace::findInternal(QWindow *w) const

This method is able to match a QWindow created by KWin to a Toplevel.
On X11 by matching winId against Unmanaged, on Wayland by matching
to internal window of ShellClient.

Finding the internal window is a commonly needed feature to e.g.
elevate the TabBox window.

workspace.cpp

@@ -1693,5 +1693,17 @@ void Workspace::forEachAbstractClient(std::function< void (AbstractClient*) > fu
     std::for_each(desktops.constBegin(), desktops.constEnd(), func);
 }
 
+Toplevel *Workspace::findInternal(QWindow *w) const
+{
+    if (!w) {
+        return nullptr;
+    }
+    if (kwinApp()->operationMode() == Application::OperationModeX11) {
+        return findUnmanaged(w->winId());
+    } else {
+        return waylandServer()->findClient(w);
+    }
+}
+
 } // namespace
 

workspace.h

@@ -127,6 +127,15 @@ public:
     Unmanaged *findUnmanaged(xcb_window_t w) const;
     void forEachUnmanaged(std::function<void (Unmanaged*)> func);
     Toplevel *findToplevel(std::function<bool (const Toplevel*)> func) const;
+    /**
+     * @brief Finds a Toplevel for the internal window @p w.
+     *
+     * Internal window means a window created by KWin itself. On X11 this is an Unmanaged
+     * and mapped by the window id, on Wayland a ShellClient mapped on the internal window id.
+     *
+     * @returns Toplevel
+     **/
+    Toplevel *findInternal(QWindow *w) const;
 
     QRect clientArea(clientAreaOption, const QPoint& p, int desktop) const;
     QRect clientArea(clientAreaOption, const AbstractClient* c) const;