x-select-font

x-select-font is a built-in function in `C source code'.

(x-select-font &optional FRAME IGNORED)

Read a font using a GTK dialog.
Return either a font spec (for GTK versions >= 3.2) or a string
containing a GTK-style font name.

FRAME is the frame on which to pop up the font chooser. If omitted or
nil, it defaults to the selected frame.