I lost a load of code I manually entered into the editor today through this bug so I made a video re-producing it.
When I tried to move control to a region that was too small it drops it back to the original region. If you then try to move this control outside the region upfront completely crashes and becomes unusable.
Youtube turned the video into a blur so here is a link to mp4 on dropbox: https://dl.dropboxusercontent.com/u/19226543/control.mp4
Also if you don't try and move it back to the top you can get a weird error where it clones itself but you can only select one of them. When you save and go back to page both will be gone.
The region at the top of the page is a global region if that makes any difference.
I'll be careful not to do it again but I think it really needs to be fixed as losing code is frustrating.