When you click on an image to preview it in the image asset editor, it expands to maximum size and there's no way to close it via UI. A page refresh is required.
It's not exactly site-breaking, but one misclick means a whole bunch of finagling and hassle to reopen closed windows in the session. Please make it so re-clicking the blown-up image element closes it or add a close dialog.
Customer support service by UserEcho