KMessage is an xmessage clone: it displays a message (specified as a parameter,
read from a file or piped to standard input) and group of buttons in a dialog
and returns a value based on the selected button.

Features:
an option to center the dialog on the desktop or to position the upper-left
corner of the dialog near the mouse pointer;
the option to output the button which was clicked to standard output; and
the option to specify a timeout, after which the dialog is automatically
cancelled.