Key_Down and all that nonsense!

To the point:
I have a event listener that manages all my key down events. Suppose I have two keys listened for. When Key A is down a variable is incremented. If key B is held down that variable is set to 0. In my case if someone holds down Key A - the variable increments over and over and over again to infinity. Using key_down events, pressing Key B while holding down Key A sets the variable to 0 and that’s the end of that. I want to preserve Key A being held down so that after pressing Key B while holding down Key A the variable increments without pressing Key A again.

I hope that is clear.
Thanks!