Index > Open in separate panel should toggle, not proliferate

[allanaaa]

To replicate: Open the Mirador live demo, toggle the sidebar on a window, click Index, then click the "Open in a separate panel" button at the top right of the Index sidebar. Do this repeatedly and you'll get multiple "Index" panels on the right of the viewer.

Instead, the "Open" button should check to see if the panel is already open, and close it if so. Or, if you're switching from Item list to Thumbnail list, it should flip the panel to the other instead of opening a new panel.

[ggeisler]

I think I understand the motivation behind this suggestion (it's annoying to have a duplicate of a panel you already have open) but it would preclude the user from intentionally having multiple panels visible (for example, maybe the user wants to have both the Index and Thumbnail list panels visible and handy for use while working with the canvas resource).

If we could detect which type of panel is already open and just not open a duplicate of it when the user tries to do it, that might be acceptable, although even then I worry about this preventing the user from doing something they might have a good reason for doing.

Overall I don't see trying to prevent what might be considered user error (trying to open a panel they already have open) is a good tradeoff when it would remove the ability for the user to intentionally work with multiple panels in a flexible way.

[enriquediaz]

It certainly sounds like making this change would replace one moderately unexpected behavior for another. Maintaining flexibility for the user is the priority.