I cannot center a widget using GBin.alignment

Learning
1

Hello fellow OCaml-ers :camel: ,

I discover the joy of LablGTK 2.18.14 :grinning_face_with_smiling_eyes:
My tiny Squava toy GTK2 GUI :

When i rezise the window, the GtkDrawingArea gets stuck at top-left corner instead of being relocated at the window center.
I can’t decide whether i do something wrong or there is a bug in GBin.alignment.

2 
-let center = GBin.alignment ~xalign:0.5 ~yalign:0.5 ~packing:vbox1#add ()
+let center =
+  GBin.alignment ~xalign:0.5 ~yalign:0.5 ~xscale:0.0 ~yscale:0.0
+    ~packing:vbox1#add ()

centers it for me.

3

I confirm it centers :head_shaking_vertically:

Kind of magic.

I also corrected let asize = 246.

Thank you.