Sets our main struct and passes it to the parent class.
Get the main Gtk struct
the main Gtk struct as a void*
Create a new sub-class of #GST_TYPE_FLAG_SET which will pretty-print the human-readable flags when serializing, for easier debugging.
the main Gtk struct
A fundamental type that describes a 32-bit flag bitfield, with 32-bit mask indicating which of the bits in the field are explicitly set.