Warn when FindWindow needs to check other processes windows.

windows/win.c

@@ -1562,6 +1562,10 @@ static HWND WIN_FindWindow( HWND parent, HWND child, ATOM className,
         }
     }
     retvalue = 0;
+    /* In this case we need to check whether other processes
+       own a window with the given paramters on the Desktop,
+       but we don't, so let's at least warn about it */
+    FIXME("Returning 0 without checking other processes\n");
 end:
     WIN_ReleaseWndPtr(pWnd);
     return retvalue;