use checkOffscreenClient for half-maximized clients

geometry.cpp

@@ -1034,6 +1034,10 @@ void Client::checkWorkspacePosition(const QRect &geo)
     if (maximizeMode() != MaximizeRestore) {
         // TODO update geom_restore?
         changeMaximize(false, false, true);   // adjust size
+        const QRect &screenArea = workspace()->clientArea(ScreenArea, this);
+        QRect geom = geometry();
+        checkOffscreenPosition(geom, screenArea);
+        setGeometry(geom);
         return;
     }