legacy flag is problematic
Pd-l2ork has a "-legacy" flag to use a positioning algorithm from Pd Vanilla for iemguis. Essentially the iemguis have always been positioned incorrectly, and Ivica fixed this to make them align properly.
The problem is that graph-on-parent abstractions typically have iemguis close to the edge of the gop border, so a few pixels difference in positioning can actually keep the iemgui from displaying on the parent.
Another problem is that OSX users can't easily set a "-legacy" flag at startup.
One solution would be to use one of the bits in the flag from the canvas arguments to specify that a particular canvas should display iemguis in "-legacy" mode. Essentially a "0" would mean "-legacy" mode, and a "1" would mean no legacy mode. That way Purr Data/pd-l2ork could set the bit to "1" when creating a new canvas and save it. That way any gop abstraction written in Pd Vanilla will default to legacy mode and get drawn correctly.
Only problem is that it wouldn't work in the other direction without changes to Pd Vanilla.