don't leave quick tiling for FS windows

REVIEW: 107317
BUG: 309170

kwin/geometry.cpp

@@ -2544,7 +2544,9 @@ bool Client::startMoveResize()
     // when starting a move as the user can undo their action by moving the window back to
     // the top of the screen. When the setting is disabled then doing so is confusing.
     bool fakeMove = false;
-    if (maximizeMode() != MaximizeRestore && (maximizeMode() != MaximizeFull || options->moveResizeMaximizedWindows())) {
+    if (!isFullScreen()) { // xinerama move across screens -> window is FS, everything else is secondary and untouched
+        if (maximizeMode() != MaximizeRestore &&
+            (maximizeMode() != MaximizeFull || options->moveResizeMaximizedWindows())) {
             // allow moveResize, but unset maximization state in resize case
             if (mode != PositionCenter) { // means "isResize()" but moveResizeMode = true is set below
                 if (maximizeMode() == MaximizeFull) { // partial is cond. reset in finishMoveResize
@@ -2563,6 +2565,7 @@ bool Client::startMoveResize()
                                 double(moveOffset.y()) / double(before.height()) * double(geom_restore.height()));
             fakeMove = true;
         }
+    }
 
     if (quick_tile_mode != QuickTileNone && mode != PositionCenter) { // Cannot use isResize() yet
         // Exit quick tile mode when the user attempts to resize a tiled window