SLgtk indicates version information in the variables:
_gtk_module_version An integer containing the value
(10000*major_ver) + (100*minor_ver) + micro_ver
_gtk_module_version_string A string containing the value
major_ver.minor_ver.micro_ver
As a user convenience SLgtk also indicates the version of Gtk
against which it was built:
_gtk_major_version
_gtk_micro_version
_gtk_minor_version