Feature Request: Synchronized/Combined Interactive Browsers for Comparing and Annotating Multiple Signals

Describe the new feature or enhancement

I would like to request a feature for the interactive browser (Raw.plot(), Epochs.plot(), etc.) that would greatly enhance workflows involving signal comparison and annotation.

Feature Description:
It would be extremely helpful to have the ability to open two (or more) MNE interactive browser windows—such as for a raw and a filtered signal—and have their navigation synchronized. Ideally, this would include:

• Synchronized time navigation: When scrolling or zooming in one browser, the other(s) follow to the same time segment.
• Combined annotation: Optionally, the ability to annotate both signals simultaneously, or to view/edit annotations on both signals in parallel.
• Stacked/linked view: Option to display two signals (e.g., original and cleaned) in a single browser window, stacked or overlaid, with full annotation and navigation features preserved for both.

Describe your proposed implementation

• Add an API to link multiple browser instances for synchronized navigation and annotation.
• Add a mode to Raw.plot() to accept multiple Raw objects and display them in a combined/stacked view with shared navigation and annotation tools.

Describe possible alternatives

Currently, this is only possible by manually aligning two windows, which is cumbersome and error-prone, and does not allow for synchronized annotation.

Additional context

No response

Start by reading the interactive-browser entry points named in Raw.plot() and Epochs.plot(), then examine how navigation and annotations currently work across separate windows. Done requires a defined approach for synchronized time navigation and the requested annotation behavior, either across linked browsers or in a combined view.