GTK2 API stability

["Lawrence Nakamura" <ln imap cc>]

Hi,
How stable is the GTK+ 2.x API? By stability, I mean:
1) How sure can I be that programs written against GTK 2.x will work
unchanged with 2.y?
2) In particular, I notice GTK/GLIB uses lots of #DEFINE macros for
constants. Do these constants ever change? (b/c if they do it'd require
a recompile, no?)
3) Are there currently plans for another major version change? (ie, GTK+
3.0)

regards,
Lawrence Nakamura