What is GTK or xorg-x11-sdk? [SOLVED]

[Dave Gutteridge]

>If you're trying to build software, what you'll be missing is the
>"development" files, required for software development. Depending on
>whether the project you are building requires version 1 or version 2 of
>the GTK toolkit, you'll be needing to do either:
>
># yum install gtk+-devel
>or
># yum install gtk2-devel
>

Thank you. This was what I was missing.

Dave