I had a bit of a dig and it turns out g_value_set_boxed as used in gperl_value_from_sv will copy a GtkRequisition. This means if you call chain_from_overridden with a given Gtk2::Requisition then the superclass code doesn't get the pointer to that one, but instead to a copy, so whatever values it sticks in are lost. I can't tell at what stage that arg ought to be treated as an "output", or whose job it ought to be. It doesn't look terribly language-binding friendly. At any rate perhaps a couple of words for the Gtk2::Widget docs (though my bad luck continues, "=for position" doesn't seem to do what I thought it might).
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GtkWidget.xs.size-request.diff
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