feat: Add option to only show open windows on the current workspace

[jacobgkau]

This exposes in the GUI an existing dock option to only show open app windows that are located on the current workspace. As a mouse-centric, non-tiling user, when I'm working on multiple projects or tasks, I generally have their respective windows separated out by workspace and I often use the dock to switch between overlapping windows. However, without this option, I often have to sift through many open windows that are on other workspaces and are unrelated to the current task. This option makes workspaces (and COSMIC by extension) more useful to users with this workflow.

An example of how this looks/works:

https://user-images.githubusercontent.com/7199422/194153159-9b842c6f-3f27-43b7-8a2f-1a7bab98e499.mp4

The copy, position, etc. of the option can be adjusted if needed.

[leviport]

I'm a keyboard-centric tiling user who also prefers this configuration :+1:

[WatchMkr]

We can consider this feature when the UX team starts designing the dock for COSMIC. It would be best not to add features that may not make the cut and require additional implementation thus moving the goal post out further to reach parity for the COSMIC release.

[jacobgkau]

For what it's worth, I think this feature would make sense to include in COSMIC Epoch as well. This is possible in KDE Plasma, upstream dash-to-dock, and is also the default behavior for the Windows taskbar. Not having it seems more like a disconnect between the dock and workspaces features.

[jacobgkau]

We've also had a few requests for this in various forms on the subreddit (the first two specifically about this dock feature, the last two also including other workspace isolation considerations that UX may find interesting):

• https://www.reddit.com/r/pop_os/comments/rq9qh1/any_way_to_make_the_cosmic_dock_show_only_windows/
• https://www.reddit.com/r/pop_os/comments/uj3jhn/is_it_possible_to_make_the_dock_only_showcycle/
• https://www.reddit.com/r/pop_os/comments/s2gvn2/what_is_the_point_of_workspaces_if_application/
• https://www.reddit.com/r/pop_os/comments/nubt4u/workspace_isolation_feature_request/