Small bug

[Pierre-Yves Chibon]

Hi,

On my keyboard I have a key on the right side of the space bar, between
the alt+gr key and the right ctrl which most of the time emulates the
right mouse click.
If I press this button on subsurface, I end up with:
Segmentation fault (core dumped)
This whatever the selection and nicely always reproducible.

Let me know if you need more information and if I can help debug it.

Pierre