After make install the gtkmm, I run the gtkmm-demo which installed in /usr/bin. 
the application reports that image files open failed (gif,jpg,png)

I checked the source code in demo directory, and found most of example source that
require to open image file only hardcoded the image name, which means the gtk-demo will look for the image on current directory.

I doubt this is wrong, as there is a function defined in demo-common.h demo_find_file, by calling this function, the resource file can be located either in current directory or the user can define the environment variable DEMOCODEDIR to tell the application where can find the resource.