How to detect a container resize event in GTK

I’ve scoured google but came up with nothing.
I’ve done the following:
id = signal_connect(alig, “check-resize”) do widget, event
println(“The window was resized”)
where ‘alig’ is a GtkAlignment to which I add a Canvas at run-time.

Can’t find “check-resize” anywhere in the docs. “size-allocate” is the event I’m after