gtk:button-new-with-mnemonic (label)

label -- a string for the text of the button, with an underscore in front of the mnemonic character

The new gtk:button widget.

Creates a new button widget containing a label with a mnemonic. If characters in label are preceded by an underscore, they are underlined. If you need a literal underscore character in a label, use '__' (two underscores). The first underlined character represents a keyboard accelerator called a mnemonic. Pressing Alt and that key activates the button.