Set the top_popup global variable to zero in MENU_ExitTracking(),

fixing MENU_IsMenuActive() and therefore VK_F1 WM_HELP message
generation.

controls/menu.c

@@ -2869,6 +2869,7 @@ static BOOL MENU_ExitTracking(HWND hWnd)
 
     SendMessageW( hWnd, WM_EXITMENULOOP, 0, 0 );
     ShowCaret(0);
+    top_popup = 0;
     return TRUE;
 }