Gex is designed for GNU Linux and Solaris systems. It is possible that it compiles on other POSIX compliant systems but I haven't tested that. Probably later with some help from SourceForge compiler farm I will try :)
Currently Gex WILL NOT run successfully under Win32 even if you manage to compile it using Cygwin, Mignw32 or other compiler.
Later I will do my best to make Gex more portable, but now it is a bit too early for it.
Compiler
gcc 3.1 or newer is highly recommended, preferably 3.2. Gex compiles fine with gcc 2.95, but I don't test it too much so I don't guarantee that everything works fine. To build Gex from tarballs you need a C++ compiler and some libraries.
Gex is developed using gcc 3.2. It should compile fine with all gvv 3.x versions. Also gcc 2.95 doesn't complain while compiling Gex but I do not test Gex at runtime with this compiler, so I guarantee nothing. I recommend using gcc 3.2.
Libraries
Gex depends on Gtk+ 2 and Gtkmm 2. These libraries also have some dependencies, but I will not list them all here.
Here is a simplified dependency graph:
LibBoost C++, version 1.21 (preferable >= 1.28), probably older versions would work fine, but I did not test it)
Gtkmm2, version 2.0.0 (preferable >= 2.0.2)
Gtk+, version 2.0.5 (preferable >= 2.0.9)
Glib, version 2.0.4 (preferable >= 2.0.7)
other Gtk+ dependencies: Atk, Pango, Pkg-config etc...
LibSigC++ version 1.2.0 (preferable >= 1.2.2)
Libraries compatibility
Remember to compile libsigc++ and gtkmm with the same c++ compiler that you are going to use to compile Gex. For example all binary Debian packages are compiled with gcc 2.95, so you also must compile Gex with this compiler if you use binary packages.
It is possible to have two version of the same library compiled with different compilers. You can use LD_LIBRARY_PATH and PKG_CONFIG_PATH environment variables to choose which libraries should be used during configure and run time.