Thats the spirit ! De-Windoze the world!
What made you choose gnome over KDE? (curious, no flames ! haha )
Dependency issues are vast in the world of linux... Alot of the time you have to install new/older versions of programs you already have installed so others will work. I'd say read the README for GTK and make sure the proper version of glib is installed. Also check all other dependencies it requires and double check those. Its common place to have to install new things you've never heard of before installing programs you've never heard of to install the program you want to! lol
Each program seems to have its own method of checking the version (as i learned when compiling a kernel for the first time), I don't recall offhand what it is for glib. A lot of the time you can just exec the program with no switches (options like -x) and it will give a usage statement. The version is usually there.
A piece of advice... if the program/library/whatever is a newer version then the one required, don't assume it will work hehe.
Sorry for my inability to help efficiently/make sense of what I'm trying to say, I'm new to troubleshooting, this is the first board I've ever attempted it on!