xcode interface builder - view sticks to the mouse

For some reason I cannot get drag and drop any view right now. I can drag, but then the view just sticks to the mouse - cannot drop!:D

Happens on Xcode 6.3 (6D570), OS X Yosemite 10.10.3 (14D136), MBP15 mid2010.

I've restarted Xcode several times - no change. I guess it's a bug in this update?