Comment 0 for bug 1270351

1. activate the selection tool,
2. alt + scroll with the cursor on the canvas
3. switch to the node editing tool,
4. switch back to the selection tool,
5. alt + scroll with the cursor on the canvas,
6. crash with this terminal message:

Program received signal SIGSEGV, Segmentation fault.
0xb64debd0 in __dynamic_cast () from /usr/lib/i386-linux-gnu/libstdc++.so.6

It seams to crash quickly when switching to and from the node editing tool,
but it happens with all tools, sometimes it takes 2 or 3 tries when
switching to and from the other tools but eventually it crashes.

Tested with r12945
on linux mint 15 32bit