Crash when exporting structure just made out of vanilla blocks custom birch tree after changing biomes i was seeing what apply presets does and when i clicked it did something then crashed with this error http://pastebin.com/5yZXPX9R Seems it isnt repeatable maybe it was a one off

I think this was fixed in f910438 (and possibly one of the earlier commits). It was caused by using the mouse wheel to scroll.

But just in case, if it was not please do reopen the issue.