Almost OT: Pushbutton switch latching

[jpero at sympatico.ca]

Look for row of mechanical pushbuttons that you only can push any of 
button while any one of other 3 buttons even is pressed pops out.

I see this on older audio stuff.  Usually 3 to 5 ganged together and 
stays on but you could use tact button (they come in different length 
of button itself) touching the rear end of the pushbutton (these 
ganged buttons have open frame on back btw.) so you get momentary 
aaction when pressed but button that was pushed stays in but not 
closing the tact switch because of play  in the latching mechanism.   
Got it?

Cheers, Wizard