I spent 3 days trying to get the color tags to draw in a row. This isn’t supported in menus so I spent a lot of time stepping through the code to get this far. I’ve gotten stuck on the highlights (and a few other issues), and I’m not sure if the route I’ve taken is the best. I’m putting this aside for now since it isn’t a priority. Maybe some day I’ll come back to this. 
I’m going to chat with my mentor and other UI team devs to see what I should do here. I do think having the color tags as icons in a row is the best option. I learned lots about the UI Layout and alignment code though!
I’ve also been putting together a sort of “overview” of my project. Now that we have reached the halfway point it’s time to start refining the features I’ve written so far. In addition to everything I’ve done, I want to make a detailed plan for after the summer of code.
There have been great suggestions (we are at 450+ replies!) throughout the summer; it’s obvious that the outliner is complex and needs attention. Most of my project this summer involves adding features to the outliner, but we also need to keep the existing behavior consistent. Adding a new feature often causes conflicts with existing behavior, or other parts of my project. Here are the areas I want to clearly define:
- Selection. Much of this was cleaned up last summer, but there are still a few edge cases that would be great to fix.
- Context menu: how actions are performed.
- Is new data created in the active collection or next to the selection?
- Make actions apply to the entire selection.
- Drag & drop: Consistent behavior, modifier keys, more clear drop targets, etc.
- Highlights: How to indicate active, selected, active/selected inside of a closed hierarchy, searched, drop targets, etc.
- Layout: row icons, popover, restriction toggles, mode tabs.
- Extra information: linked/instanced state, hierarchies, etc.
Most of these goals aren’t specific features; rather they are behaviors that should be consistent and well thought out.
Thanks again for reminding me of this. I fixed this today and it will be available in the daily build in a few hours.