GTK 2.2 compatibility and GTK 2.4+ widgets

[Gabriele Greco <gabriele greco darts it>]

There is a way to know if a widget is available only in a particular 
version of GTK 2.x?

I'm developing an application on a GTK 2.4 machine with the target to be 
able to run it also on GTK 2.2, since  most distributions of the past 
two years still has that installed.

It's the second time I have to disable a feature I've added since I've 
discovered (compiling on a GTK 2.2 machine) that the widget doesn't 
exists on that! (gtk_combo_entry, gtk_color_button...)

It will be nice to have in the widget documentation the GTK version in 
whitch a particular widget has been introduced.

Bye,
 Gabry