When you press a button gadget (control button) it will usually display a child form or invoke a call-back - typically a PML Form method.

(See Gadgets that Support Pixmaps for more about pixmaps).

You can specify the width of the BUTTON independently of any tag text string it contains using the WIDTH syntax. You can also define its height with the HEIGHT syntax, allowing you to define textual BUTTONs taller than a single character in height.