I am struggling with what I believe to be a very simple task. I merely wish to view the framing of multiple cameras at the same time. It seems that it is not even possible to view the camera framing and a User Perspective view at the same time. This is shocking to me, I've been using 3D programs since 1991, and this is a new low in usability.
I am aware of the options "'n' > View > Local Camera" and "'n' > View > Lock Camera to View". These do not help me. The "Local Camera" only affects the top right panel. The backtick key to load the "pie menu" only affects the top right panel. It appears that Blender has extremely limited options for controlling the Quad viewport layout, and we can only change what appears in that top right panel.
The only workaround I have found is to copy the viewport "Area". From there I can choose whatever I want in that "Area". But it is a poor solution because 1) it duplicates all of the UI widgets (super cluttered) and 2) it limits my ability to go fullscreen. The new child "Area" is always visible.
I can also copy the viewport "Area" out to a floating window, which is better, but still, this is a poor solution to a problem that should not exist. I should be able to choose whatever I want in any of the four Quad panels, like in any other major DCC.
Please tell me that I am missing something and that there is a way to make Blender view more than one perspective view at the same time, in the same "Area".