• Triangle Interface doesn't work

I would like to give some feedback about ...

From: http://www.checkio.org/mission/triangle-angles/solve/


Mozilla/5.0 (X11; Linux x86_64; rv:37.0) Gecko/20100101 Firefox/37.0

If I try to change the triangle in the bottom, the point I click on jumps to the top left corner (see attached picture) I can't drag it or move it anymore.