In DF 9.2 beta 1, Windows 10 1703, the Titlebar buttons seem to get left over and are slow to vanish.

If I shake a Window, the primary monitors windows all minimize, but the titlebar buttons hang around for a few seconds.

If I press Win+L, the computer locks, but sometimes titlebar buttons (e.g. on the DF Settings dialog) remain on the lock screen and haven't vanished after I waited five seconds.

I have seen the same issue from time to time. It also may be the cause of my earlier defect note:
My previous discussion

Debug info attached, time was 5/24/18 16:43.

I shook a small window on secondary monitor, all windows on primary monitor minimized, titlebar buttons stayed behind, I moused over each set of titlebar buttons and they vanished, then I stopped logging and exported.

Note: Using DF Pro 9.2.