gboolean gtk_size_group_get_ignore_hidden ( GtkSizeGroup* size_group )
Returns if invisible widgets are ignored when calculating the size.
Measuring the size of hidden widgets has not worked
reliably for a long time. In most cases, they will report a size
of 0 nowadays, and thus, their size will not affect the other
size group members. In effect, size groups will always operate
as if this property was