The valgrind software is used to check for memory issues in gml4gtk, see https://valgrind.org/

To fix all valgrind messages is the fastest way to prevent bugs and fix hidden bugs.

Also the valgrind callgrind program can generate callgraph info which can be converted to dot graph data using gpof2dot at https://github.com/jrfonseca/gprof2dot     or  https://github.com/zenkj/callgrind2dot

The valgrind messages with gml4gtk come from the external GTK+ libs and not gml4gtk and maybe some day they can also these issues fixed in gtk+.

These dot graph files can be used with gml4gtk and it looks like this:

callgrind
gprof2dot
gprof2dot
gprof2dot
grpof2dot