I don't mean locking the graph viewport, I mean locking the contents of the macro (I suppose, locking the macro itself) so that it becomes read-only. I have a bunch of small utility superunits I'm using and it can be easy to break things. I can imagine it would be even worse with multiple people working. In unity I use some add-ons to allow me to lock objects on the hierarchy and it greatly improves my flow and reduces errors.
The locking could be done from a little radio button on the graph inspector near the name and description and also, if possible, from the project inspector by right clicking on the macros. The lock state when that graph is selected could be shown by greying out all the nodes and/or having some noticeable red label or lock icon to indicate it:
You can still select units, but only to copy:
Of course since we can have macros within macros as superunits, you'd also be able to lock/unlock those superunits source macros by an option in the node's context menu. The lock state of the unit could be shown with a little icon on its corner. Here, the parent macro/graph is unlocked, but the selected superunit is locked.
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