Fix issue #8800.
Fix issue #8800.

Gtk complains that we are not using gtk_scrolled_window_add_with_viewport,
so let us do.

JasonGross/coq,JasonGross/coq,Matafou/coq,maximedenes/coq,maximedenes/coq,ejgallego/coq,SkySkimmer/coq,silene/coq,ejgallego/coq,coq/coq,silene/coq,JasonGross/coq,Zimmi48/coq,silene/coq,ppedrot/coq,Matafou/coq,gares/coq,coq/coq,JasonGross/coq,maximedenes/coq,ejgallego/coq,SkySkimmer/coq,Matafou/coq,coq/coq,gares/coq,ppedrot/coq,ppedrot/coq,maximedenes/coq,ppedrot/coq,Zimmi48/coq,ppedrot/coq,maximedenes/coq,Zimmi48/coq,gares/coq,Zimmi48/coq,ejgallego/coq,gares/coq,coq/coq,SkySkimmer/coq,gares/coq,SkySkimmer/coq