This thread predated the release (later in the autumn of 2015) of SketchUp 2016 which debuted a Windows edition using the ol’ Microsoft tray / inspector panel system. The system has a convention (promoted by MIcrosoft) of creating a “Default Tray” populated with all of the possible dialog panels. (It is however expected that users will create their own trays having the selection of panels they desire, arranged however they like.)
So at the time (June 2015) the team would have been working on the 2016 version for half the year (or abouts.) Looking back, it is a no brainer that they needed to decide how to order the panels in the “Default Tray” and decide where to dock that tray for the “as installed” setup.
Realize that at this point (June) they’ve got about 4 or 5 months until release, to finalize the code base, do all the testing phases, and final fixes to any bugs introduced by new functionality, and build up 2 platform editions into like 12 languages (24 installer packages.)
Since then, we’ve also seen the beta and release of the 3 SketchUp for Web editions. I don’t know if they started playing with it that early or not. But it should also be obvious that this “study” helped in the design decisions of the browser based interface.
There is no limit if they are all “on subject”.
A question you did not ask… “from the user’s perspective, what effect did it have ?”
You can see my “before” screen shot above.
And partial screen captures of the right-side docked inspector trays in this other topic post about trays.
I went from having things wrapped from the top left down around the bottom, to having the trays docked on the right. (I came from AutoCAD and always liked the slide out property panel on the right in AC.)
I also have the Outliner and the Help Instructor autohidden into the left side margin, so they’ll slide out into view when I hover over their tabs.
Now my Ruby Console is the only thing floating (and since then SU2015,) I’ve used 2 displays so the console is often on the other display.
That’s subjective and John’ll need answer this.