Include path with variable in Eclipse

Question

I try to use gtkmm on Windows using Eclipse and MinGW. In order to set the gtkmm include paths I defined a build variable at "Project Properties -> C/C++ Build -> Build Variables".

The varible is called "gtkmm" and is set to "C:/gtkmm".

Now I try to add all paths at "C/C++ General -> Paths and Symbols -> Includes".

But the problem is that when I enter a path like "$(gtkmm)/include/gtkmm-2.4" Eclipse recognizes it as "../$(gtkmm)/include/gtkmm-2.4" when building the project.

So how can I define those include paths? I know that I can do it at "C/C++ Build -> Settings -> C++ Compiler", but I have to add 10 paths or so and I want to export them so I can also use the exported configuration for other projects.