help page opening

[Pierrick MADE]

change sensible browser by something else as chromium/firefox

[Théo Lepage]

Using system("xdg-open http://url"); in your C code.
Is this the solution you wanted?

Edit:
I have just noticed that xdg-open may not be installed on every computer. Then, what about g_app_info_launch_default_for_uri()? See documentation.