Well, that seems to be it ! Thanks :)

On a similar note : is there a way to disable drag-moving, too ? By that I mean the ability to move elements by dragging them directly with the mouse - as this too can interfere with selection, although to a lesser extent than the manipulators mentionned earlier.

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Also, a suggestion : Marvelous Designer has a fantastic tool letting one transform straight segments into curves, like so :

https://imgur.com/5qOeAwW

To achieve a similar result in MOI one needs to add one or two new points to the middle of a sgement, select the segments, enable show points, and then dragging the points around. Having the ability to intuitively turn segments into curves like in MD (or something similar) would be fantastic really.