I don't know if you can compare Modo's palettes and tabs with Carrara's rooms. I don't think that you can get part of the materials room or modeling room into Carrara's assembly room, whereas in Modo you can pull in some new tabs just where you want them. Having said that, it's a feature with which I only started experimenting recently and am not too comfortable with yet. I guess I'm still too attached to Carrara's rooms idea
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Ciao,
Wim