I'm riding a FCU for Airbus Wilco. I studied several cases on the subject even more could not solve my problem. I made some changes in FESS code that already make my work FCU SPEED, HDG, ALT V / S
I would like to know how to use a push button to PULL and PUSH SPEED of Wilco

When pulling the button, he would change the value of speed to "- - - -" as the airbus panel does.

I believe that the airbus X also need this setting