GtkAspectFrame should have GtkLabel widget like GtkFrame
When a GtkFrame widget is created, two child widgets are also created: GtkAlignment and GtkLabel. GtkAspectFrame is a child type of GtkFrame, but the recent versions of Glade do not create any child widgets when a GtkAspectFrame is created, so that it cannot have a label, although label xalign and yalign values are available but don't seem to have any use at present.
The GtkAlignment widget should be ignored, has no effect and is deprecated. They say "The desired effect can be achieved by using the “halign”, “valign” and “margin” properties on the child widget". In the Common tab for GtkFrame however, margins have no affect. Suggest it be removed.