Label button with its keyboard shortcut

Label button with its keyboard shortcut

I know buttons could be labeled only by plaint text, but I want to label them with the letter that is their keyboard shortcut underlined. For example: Export. I have done this for radio buttons passing for example <u>L</u>ist to have List.
Besides the ugly workaround to label buttons like this: (E)xport, is there any suggestion how to obtain the underlined letter? If not, where should I enter a feature request?
I'm running latest jQuery UI version on Windows under Chrome.
Thanks for your help!
mario