Panels missing "close" controls

[dharabor]

Steps to reproduce:

1.Open an example
2. Close the default map viewport, using the vertical "..." menu in the top-right.
2. Click the viewport button in the left panel to make the map reappear.
3. Viewport is missing "..." button and cannot be closed. The same is true if we switch to over views (debug, examples etc)
4. The search trace panel now also cannot be closed ("..." controls appear, but the option is grayed out).

Suggest we always show the viewport (map or tree) and only the other panels can be added/closed. I can't see a use-case for not showing the viewport in some way. Without it, we're back to analysing logs.