-- card: 4186 from stack: in.0b2
-- bmap block id: 0
-- flags: 4000
-- background id: 3155
-- name: 
----- HyperTalk script -----
-----------------------------------------------------------------------
-- openCard
-----------------------------------------------------------------------
on openCard
  global font, fonts

  put "Geneva,Monaco,Chicago" into fonts

  put 3 into font
  set the textFont of card button "Example" to item font of fonts

  pass openCard
end openCard


-----------------------------------------------------------------------
-- doPopUp
-----------------------------------------------------------------------
on doPopUp
  global font, fonts

  get PopUpMenu( fonts, font )

  if it is not empty then
    put it into font
    set the textFont of the target to item font of fonts
  end if
end doPopUp


-- part 1 (button)
-- low flags: 00
-- high flags: A004
-- rect: left=278 top=157 right=179 bottom=378
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 1
-- font id: 0
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: Example
----- HyperTalk script -----
on mouseDown
  doPopUp
end mouseDown


-- part contents for background part 10
----- text -----
A typical script using this external function might be

  on mouseDown

    put "Geneva,Monaco,Chicago" into fonts

    get PopUpMenu( fonts )

    if it is not empty then
      set the textFont of … to item it of fonts
    end if

  end mouseDown

Don’t forget to look at the help stack’s scripts for other examples.