This is not exactly creating your own command buttons, but there is some
information here:
http://www.lebans.com/cmdbutton.htm
Any control, including a picture, label, box, etc. can have a click event.
Also, the mouse down and mouse up events of a control can be used to set the
special effect to sunken, then raised, which simulates the appearance of a
command button. There are limitations to using a control in this way (you
can't tab to it, for one thing), but in some cases it is adequate.
