[Scop-Amac]

On first Start of sketchup, when I use the menu (/extensions/Maxwell) it launch my old Maxwell Studio 3 And the Maxwell render 3. After that it's ok.

Plugin 4.1.1
Maxwell Render 4.1.0.3
Os : OS 10.11.6

[JDHill]

To some degree, this depends on what Finder wants to use to open Maxwell files, so it may help to use right-click > Get Info to set .mxs/.mxi files to open with your v4 maxwell.app, and to set .mxm files to open with your v4 mxed.app. I would also recommend downloading the current-release 4.1.2 plugin, which bundles the current 4.1.0.4 Maxwell Render.

That said, I will look into having the code reject any application indicated by Finder, if it is contained in a "Maxwell 3" folder; technically a person could choose to put Maxwell 4 in such a folder, but that would just be evil, and not worth worrying about.