Call TestHit whenever you detect a MouseUp on the card. TestHit checks the mouse location against all buttons and returns the number of the button hit (See: Creating Buttons). If none of the buttons were hit, then TestHit returns zero. The button number (or zero) is returned in "the result".
TestHit can optionally be followed by "TRUE" or "FALSE" to indicate whether hilighting should occur when a button is hit. If it is not specified, hilighting defaults to "FALSE".