if you set the labelFor property of a label to the name of a field and set the mnemonic property of the label to one of the letters in the text of the label and then go to browse mode, you can use the alt-key + the mnemonic letter you have set to jump to the field.
Just go into your developer environment on windows and press alt (or any other proper application): depending on the Look and Feel you will see letters in the text of menus in the menubar being highlighted/underlined.
If you type the letter that is underlined, that menu will be activated.
Unfortunalty, Apple did not put these keyboard shortcuts into their GUI design guidelines and therefor, they do not support it in Jave, thus we cannot support in om Mac.