Per-project view is neat.
Multiple projects view is great.
All projects view is better!
I think only unarchived projects should show up in portfolio view to prevent API heavy loads.
Or, even, only favorite projects.
Another way to do it would be:
- Step 1 show a checkbox in front of all (unarchived) projects
- Step 2 as soon as one project is added to the checked projects list, the URL takes it as a param (see #13), eg. : https://app.ganttlab.com/group1/project1,group1/project2,group2/project1, etc...
- Step 3: magic happens!