Change interface font in a GTK application at runtime without reopening windows

[Gabriele Greco <gabrielegreco tin it>]

A lot of users are asking me for the capability to change the font of an
 application runtime.

I know that the correct answer should be "change your gtk theme" or edit
the application RC file, but while this kind of answer is good with
power users, normal users often want to be able to grab a font from a
list and quickly try it on the REAL application interface without the
need of a restart.

I know that I can change the font of a single widget with
gtk_widget_modify_font(), and that I can change the font of EVERY future
widget with something like:


gtk_rc_parse_string("gtk-font-name=\"sans 13\"\n");

But what if I want to change the font of the actual interface without
having to close all the application window and open them again?

I'm quite sure it's possible since I've seen a few apps doing it. Sadly
I don't remember the apps, otherwise I'd go peek at their sources :)

I think there should be cleaner way that a full iteration on the widget
tree of every window and a gtk_widget_modify_font() Call on each widget,
isn't it? :)

Bye,
 Gabry