This option lets the user specify a difficulty level between one and fifteen
at which the next game is to be started. This option is not availible when
a game is in progress.
<li><b>Quit</b><br>
This exits the <b>htetris</b> application. This can also be acheived by the
keyboard shortcut <b>meta-q</b> or by pressing the <b>Quit</b> button on the
interface. If a game is in progress, a possible highscore is lost.
</ul>
<br>
<li>The <b>Controls</b> menu<br><br>
<ul type="disc">
<li><b>Set keys</b><br>
This opt