Thanks a lot for the quick reply!
I do know about the ability to double-click on a title bar to collapse that row of panels. What I'm looking for is a bit more fine grained, the ability to collapse individual panels like "Exposure", "Enhance", "Shadows & Highlights" without disabling them. Currently they are expanded if enabled, and collapsed if disabled. I am looking for a way to collapse them without disabling.
Interestingly, this "feature" is available in certain panels in the Photo persona. For example, under the "Effects" title, panels "Gaussian Blur", "Outer Shadow", "Inner Shadow" etc can be collapsed without disabling them. In the attached screenshot "Gaussian Blur" is enabled and expanded, "Outer Shadow" is enabled but collapsed, and "Inner shadow" is NOT enabled but expanded. The ability to expand/collapse independent of their enabled/disabled status is really convenient to me. And it would be super sweet if there is a way to automatically collapse other panels when one is expanded. And yes, I do understand that different people have different editing preferences, so if this is an option like the "Solo mode" in Lightroom, then I'm sure that everybody will be happy! :-)