[0.17.4] Bug with preview window

[Nekogui]

I was creating a new map, and pressed to see preview map, after the preview window was opened, i pressed alt+tab to se a notification on Google Chrome, and when i come back... the preview window was messed up:

print2.jpg (761.72 KiB) Viewed 396 times

So i closed the game, opened again....the preview window still buggued, and i dont know why

After some time, i unistaled and instaled the game again, tryed preview again, and the window still bugued, so i played without using preview, and 1hr after i was playing i saved and exit the game, and tryed to create a new map, when i pressed the preview window, everything was fine again:

print1.jpg (705.32 KiB) Viewed 396 times

What happened ?

Ps: English is not my first language sorry.