Revert "When undoing an arrange or showing the desktop, focus the las…

…t focused window instead of the topmost window." for issue #788.

This reverts commit 2abbe86.

src/wmmgr.cc

@@ -3590,7 +3590,7 @@ void YWindowManager::undoArrange() {
         delete [] fArrangeInfo; fArrangeInfo = nullptr;
         fArrangeCount = 0;
         unlockFocus();
-        focusLastWindow();
+        focusTopWindow();
     }
     setShowingDesktop(false);
 }