In system settings > Shortcuts > Custom shortucts, it is impossible to define button for mouse gestures higher than 9 (there is an option for defining button 10, but it does not work, only 9 and lower work). I have a mouse with button 13 (showing in xev, it is a logitech performance MX) and I believe many others like this exist. An option to map gestures to button 13 would greatly improve usability of both the mouse itself and the mouse gestures.

Reproducible: Always

Steps to Reproduce:
1. Open system settings > Shortcuts > Custom shortucts
2. Check box to eneable gestures
3. Try to assign button with greater number than 9. 10 is available, but won't work. 11 and above isn't available.

Actual Results:  
Button 10 is available, but does not work (gestures with that button won't trigger). Higher button numbers cannot be entered.

Expected Results:  
There should be at least 13 possible button numbers.