Working with fonts

[CaptainMaelstrom]

I'm a little confused about how to work with different fonts.

I'm writing a program which lets the user define which font they want displayed, but I foresee a problem.
When they pick their font, how will I know how to size my user interface elements?
Especially if the user picks a variable width font, I won't know how, programmatically, to determine user interface elements' (buttons and the like) width/height to prevent text from spilling out of the UI elements or being cut off by them.

Anyone have experience or suggestions for dealing with this?

[slime]

[wiki]Font:getWidth[/wiki]
[wiki]Font:getHeight[/wiki]

[CaptainMaelstrom]