Is the gtkmm package already installed by default? If not how do I install it on Ubuntu with all the prerequisites? Would a command line install be better? Do I need to add a repository?
No, the packages you need are not installed by default but are available in the normal Ubuntu repositories. You can use
Be sure to have the C++-Compiler installed:
For C++ programming you need to install the development version of the important GNOME libraries. Those contain the header files and additional linker information:
In addition, you will want to install the documentation packages of this libraries so you can view them in the API browser (devhelp):
I recommend you also install gnome-devel-docs to look at some demos. After installing, run
Ubuntu 11.10 comes with libgtkmm-2.4-1c2a and libgtkmm-3.0-1
libgtkmm-3.0-1 is installed by default