Help UE engine issues

[user_3d7a73a64efd0a67e4413c69dd1b126a3357e623939d7ef8959353 (圈圈圆圆圈圈圈)]

I don’t know why this white box appears on my screen panel, and then I can’t use anything, including steering and angle shifting. How can I solve this problem?

[ClockworkOcean]

Restart the editor. You’re in the middle of dragging a window.