GtkAlign has four values:
It's all good until you want to express a start or end alignment while the widget is filling all its allocation.
This is usefull mostly in transitions, e.g. to adjust the position of children in a non-homogeneous
GtkLabel work around the issue by having
yalign properties, to let their users refine how they want the content to fill its allocated space.
The heart of the issue I think is that filling isn't an alignment, it's at best its absence, and at worst a completely different concept.
What about dropping
GTK_ALIGN_FILL and instead give
fill property? That would avoid the aforementionned workarounds.
Maybe we could drop
GtkAlign completely and have a 0–1 value like for
xalign too, if judged relevant.