After some thought - even if possible, splitting 3d viewport option inside would just get messy unless it’s scalable. I looked into some other collections work and I found this as a example “ Misc Menu - Pop-Up Collection & Modifier “ instead of dragging a new 3d view he used tabs. You having a mini collections and the split window makes your method more visually diverse to quick selections and data.
The idea isn’t specific for a -property tab, it was more or less the option to open port to work with to assist in any changes without having to take more screen space… Example im thinking about modifier tab, properties, scene, asset management, meta data (ngons, tris, quads, edges, faces, color, items, id, etc), undo history timeline (could even have a smarter undo)
Expanding on this undo issue the blender community is having, would it be possible to make a collections “trash bin” (possibly that tab above) that saves and creates a cache of undo movement so we can undo quicker? I have a few ideas on this if it’s possible, definitely above my skill set. This could be extremely useful to literally everyone making more than a few cubes. I know this is a lot larger problem to solve than what it sounds, infinitely deep problem with blender, curious your take on the undo - not sure if you even wanna mess with it.
I checked out your ui addon, I like it, plan to use pieces of it with pie menu editor. Off topic, I saw your post Mesh Silhouette: My first Bmesh Operator - this looks interesting wondering if you ever continued anything with the wireframe smooth compare and silhouette? I use silhouettes in my sculpting, super useful. Sorry for the long post, Thank you.