t/264-keypress-numlock: add mouse binding test
t/264-keypress-numlock: add mouse binding test

fixes #2523

cornerman/i3,Airblader/i3-original,Airblader/i3-original,stapelberg/i3,i3/i3,i3/i3,Airblader/i3-original,i3/i3,Airblader/i3-original,Airblader/i3,Airblader/i3,i3/i3,cornerman/i3,Airblader/i3,stapelberg/i3,stapelberg/i3,Airblader/i3,stapelberg/i3,cornerman/i3,cornerman/i3,Airblader/i3-original