gimp 2.6.7 crashes after the window focus has changed.

When coloring with gimp, a crash happens when I put a pixel to the screen after revisiting the canvas after having changed window focus (eg. moving to and from different running programs). Work is lost.

I do not know what could be causing it, whether it is an upstream bug or if it is because of the environment.

(am using the provided Trisquel Gnome desktop environment with mostly default settings. fancy window rendering is turned off though.)