[Feature Request]: Display Window or Workspace on Multiple Monitors at the Same Time

## Feature Request ### Description It would be nice if it is possible to display a window or a workspace on more than one monitor. Assuming a user uses more than one monitor (e.g. the internal monitor of a laptop and a projector connected via HDMI), he/she should be able to display a window on both the internal monitor and the projector. Unlike duplicating the screen on the projector, the user also can switch to a different window on their internal screen without it being displayed on the projector. ### Use Case I would like to use this feature in Meetings. If I share a document (e.g. a browser with a website, document in the NextCloud, ..., or Excel) via the projector in a meeting and discuss/edit the content together with those present, I would like to be able to switch to another content on the internal screen (e.g. my own calendar for the next appointment coordination or another browser for research purposes) that is not visible to everyone on the projector. However, while I see the other content, the other persons should be able to see shared content. Another similar usecase would be a typical consultant/sales scenario in which the consultant has a second monitor facing the customer. The consultant should be able to share a window on the second screen while seeing the same window or another window on their own monitor. ### Proposed Solution I see more than one possible approach: 1. show a whole workspace on two different monitors (same resolution or maybe scaled) 2. show a floating window not only on all workspaces of one monitor but on a list of monitors 3. associate a tag with a monitor for the output (e.g. tag m1 = internal monitor, tag m2 = projector => a window with both tags is visible on both screens) ### Alternatives I think about writing an application which makes screenshots of a window and opens the image in an image viewer on the projector. ### Additional Information