highlighting a button upon entering

[Alexey Marinichev <lyosha lyosha transas com>]

Hello,

Just started learning gtk.  Want to write gtk gui for vim.

I didn't find it in the tutorial, could someone clarify it for me how exactly
it happens that a button is highlighted when mouse cursor enters it?

Also, is it possible to disable this highlighting by playing around with
signals?  Not that I want to use it, I'm just curious.  I tried catching
"enter" event and stopping it, doesn't work.

Thanks--

	--Lyosha