Because I have two screens I prefer the concept of multiple windows.
There is only one annoyance: EKOS is minimized together with KStars' skymap window. In don't like this behaviour. EKOS should stay open if I try to minimize the skymap window.
I'm running Kstars 3,5.1 with Catalina 10.15.7 and cannot replicate this window behaviour. "Independent Window" for Ekos/Indi viewers ON or OFF seemed to make no difference. In full screen mode Kstars filles the screen as expected. If Ekos is opened I get a floating window and once Indi is started it's in front of the Ekos window. Clicking the Ekos window doesn't cause it to move to front. I have to hide Indi (from KS tool bar) to see Ekos again,
Quick vote for why NOT to make the FITS viewer part of the Ekos/etc subsystem is that it introduces yet another potential spot for a memory leak, segmentation fault, etc in one part to take out the rest of a night's imaging session.
But agree with the general principal that there are a lot of hard to manage windows that float around and anything that I could do to "lock" them into a specific set of places would be helpful.
GSO Ritchey Chretien 12" Truss | SkyWatcher ED72
ZWO ASI 2600MC Pro, 1600MM Pro, ASI290MM and ASI224MC all-sky | ZEO EFW | ZWO OAG
Moonlite V2.5 CSL | DeepSkyDad AF3
EQ8-R | Paramount ME & MX
Nexdome | SQM LE | AAG CloudWatcher and Solo | Ultimate Power Box V2 | Spike-a-Flat
While troubleshooting yesterday I went back to 3.5.0 and DID see the integrated tabbed display you reported in 3.4.3. I guess something got tweaked slightly the wrong way... (not being a programmer, I couldn't even guess).
What I think would be a nice feature would be that once the scheduler is kicked off there would be an option to automatically focus the displayed Ekos tab that is currently active, i.e. if the scheduler starts a autofocus routine then Ekos automatically moves to the focus tab, if it starts an align routine then it moves to the align tab etc...
I know there is the summary window where we can see guiding / focusing & last capture + capture status, but for me it doesn't always display the information correctly or in a easy to view way (sometimes the last capture doesn't appear in the main window, it is difficult to follow the guiding as it's not always scaled correctly, and a few other niggles). It might just be that the summary UI window could be better.