Paul__B:
They are not pushbuttons as such - they are called "microswitches".
What is difference between pushbuttons and microswitches? And do you know why the mouse uses this for buttons and a "normal" pushbutton for the middle wheel push?
Paul__B:
They bounce like crazy. Debounce is performed by the firmware in the mouse chip. (Obviously!)
Somewhere I have read this
should be bouncless. Because the contact first bounces between Vcc and NC, after it settles at NC and finally bounces between NC and GND. The capacitance of the input pin and traces and the switch does the debouncing of the NC periods. But I have not tested this myself.