Edward,

In the KeyPress method just issue a NODEFAULT for the keys you want to filter out:

TextBox::Keypress( nKeyCode, nShift )
if ( nKeyCode = 65 )
   * filter out 'A'
  nodefault
endif

>I'm trying to cancel a character string produced by a keypress of a programmable keyboard from being sent to a textbox by validating the first character in the string. Thus far the only methods I've achieved are (1) to let the string write to the textbox and then validate the leftmost character and input an empty string or (2) to disable the textbox by validating the first character in the keypress method of the form. The ideal would be to clear the keyboard buffer from the keypress method, but that doesn't seem to work.