>>>>> "Sam" == Samuel Tardieu <sam at rfc1149.net> writes:

Sam> However, I want to make sure that when the RectangleMorph gets
Sam> moved, the PasteUpMorph gets moved as well, to have the arrows
Sam> follow.

Found. I now use another RectangleMorph instead of a PasteUpMorph and
#sticky: instead of #locked: on the extension, and everything is fine.

  Sam
-- 
Samuel Tardieu -- sam at rfc1149.net -- http://www.rfc1149.net/sam