Strange glitch I discovered.

[Kyleallt]

1. Make a boss that talks to you and ends the level (Bowser Defeat) if it dies
2. Defeat it while using Level Editor's test mode
3. While the text box appeared, go to Events
4. Delete the boss defeated event
5. Stop talking (space)
6. The glitch happens.

Also, the glitch is that the background turns black, your cursor moves upwards along with every object, and you can only go out of the level by closing the window. Please, save your level before you do this.

[Valentine]

The same glitch happened to me but with a friendly boom boom who talks, at level start

[Imaynotbehere4long]

This is actually a pretty common bug in SMBX, so much so that there are various ways of triggering it, most of which are unintentional:
http://www.smbxgame.com/forums/v ... =35&t=3663