Describe the annoyance
Before Rerun 0.27, double clicking a frustum, and then zooming out, would change the up-axis of the 3D view to the up-axis of the camera frustum. This was quite handy, because often images / cameras are somewhat upright; but the world might be oriented in some other (possibly unknown way).

In general it was possible to control the 3D camera after double clicking, which (to me) felt quite natural. Now, all controls are disabled and zooming out resets to the previous view.

Not sure if this was a deliberate change; if it was, it would be nice to keep both functionalities somehow (e.g., Ctrl+Z to restore the previous view; manipulating the 3D view should have the behavior from 0.26).

To Reproduce
Double click frustum, zoom out.
View resets to what it was before double clicking, instead of maintaining the new up-axis (zooming out from the camera view).

Expected behavior
I preferred the old behavior. Now there is no way of quickly setting the up-axis of the world based on a camera in the world. Previously double clicking the 3D view already provided a way of resetting. Ctrl+Z works in the new version to restore the previous view.