But when would I make it false.
Just before you test for any keyboard input. That way you don't have to "test for nothing" because "nothing" becomes normative.
EDIT:
Like this - see how you can do things based on no key having been pressed after the input routines.
Graphics 640,480,0,2 SetBuffer BackBuffer() keyPress=False output$="Blah" x=320 While Not KeyDown(1) keyPress=False If KeyDown(203) keyPress=True x=x-1 If x<-150 Then x=639 output$="Coo, I'm going left!" EndIf If KeyDown(205) keyPress=True x=x+1 If x>639 Then x=-150 output$="Coo, I'm going right" EndIf If keyPress=False Then output$="Awww, I am idle :/" Text x,240,output$ Flip Cls Wend