This causes strange behaviour depending on which panels have been open or closed.

Take BEBB (https://bebb.jinntec.de/home.html), an app that displays two columns: a transcribed view and a facsimile. The transcribed view can be a page-by-page or a whole view. If the page-by-page view is open, we want the pb-navigation buttons in the toolbar to show up. All communication is going through one channel only: all subscribe and emit are the same.

The problem is that the whole view is the initially open one. If you then use the facsimile to navigate between pages, the whole view is updated, emitting a pb-update that the document is opened in the all-pages mode. This then triggers the facsimile view to update to the first page. Even if the whole view is closed. There are small work-arounds in place in some cases, but they do not cover all ways to change the navigation (they cover the pb-navigation buttons by not using the facsimile to navigate).

Can we deactivate hidden panels? This should make the app a lot more predictable: everything counts as an initial open and hidden panels do not affect application state.