front end - How to find out available fonts from within Mathematica?

How to find out available fonts on the system from within Mathematica? When I do

Style["foobar", FontFamily -> "Foobar"]

how do I know which font the displayed output is using/falling back to use?

Answer

The relevant line from this SO post:

fontlist = FE`Evaluate[FEPrivate`GetPopupList["MenuListFonts"]];

Update: The content of the "MenuListFonts" list is system-dependent. In Windows Vista, I get a list that contains only FontFamily:

 Panel@Row[fontlist[[;; 60]] /.
 Rule[x_, y_] :> Style[ToString@x, 14, FontFamily -> y],  " \[FilledSquare] "]

On a Mac system, it appears that the list contains tuples of FontFamily, FontWeight and FontSlant. That is,

fontlist /. Rule[x_, y_] :> Style[x, 20, FontFamily -> y] 

gives