Voilà pour xev :
nicolas@nicolas-fixe-xubuntu:~$ xev -event mouse | grep Button --before-context=1 --after-context=2
ButtonPress event, serial 25, synthetic NO, window 0x4e00001,
root 0x4d8, subw 0x4e00002, time 63195089, (36,44), root:(907,493),
state 0x10, button 8, same_screen YES
--
ButtonRelease event, serial 25, synthetic NO, window 0x4e00001,
root 0x4d8, subw 0x4e00002, time 63195290, (36,44), root:(907,493),
state 0x10, button 8, same_screen YES
--
ButtonPress event, serial 25, synthetic NO, window 0x4e00001,
root 0x4d8, subw 0x4e00002, time 63197945, (48,41), root:(919,490),
state 0x10, button 9, same_screen YES
--
ButtonRelease event, serial 25, synthetic NO, window 0x4e00001,
root 0x4d8, subw 0x4e00002, time 63198073, (48,41), root:(919,490),
state 0x10, button 9, same_screen YES
nicolas@nicolas-fixe-xubuntu:~$