How do I ensure I have gtk+ installed?

[Kipton Moravec]

A program I have requires gtk+ 2.4.x or later to recompile it.

So to verify I typed:

sudo apt-get install gtk+

E: Couldn't find package gtk

So what is the most current package called?

I searched Synaptic Package manager for gtk+ and did not recognize it
there either.

-- 
Kipton Moravec AE5IB
"Always do right; this will gratify some people and astonish the rest."
--Mark Twain