What is the font size of labels displayed in a uimenu ?

How to know the font size of an uimenu label ?

uimenu has none of the following properties: FontSize, FontUnits, Extent

Property Position is a scalar value indicating the relative position in parent uicontextmenu.

My goal is to determine the overall height of a contextmenu with (too) many uimenu items (to appear in the screen).

Help on Uimenu Properties

See also : "My uimenu list (a vertical child menu list) is too long to fit on my monitor"

Thanks for any help