Yes, inventory management appears when waiting for a game, on game load I get the home screen.
That's the Inventory screen, see the profile "badge" on the top left... but yeah, I think your question demonstrate what I'm saying about a not optimal UI; notice the lack of highlighting on the main menu, which makes it confusing knowing in what section you are.
Fiddling around I found out you can't exit the game if you are on an Option or Stats screen... which I can understand why it's like that (for the former), but the screens looks like any other: I think there should be a clear separation (like overlay window) if you want this sort of behaviour. Plus Options screen doesn't have tabs like the Inventory
I find these dropdowns menu are quite annoying anyway... I'm now curious how they have laid out the console version.
Or why the mapcycle screen is so big, with the "Ok" button so far away, when you just can have a few to select from anyway... if at least you could hit Enter to confirm a mapcycle of choice, but no. And I think you could start a search of a new server more quickly, straight from the in-progress game, or wasn't? Cos being forced to exit to Main Menu to search for a game it's stuff from the stone age.
I dunno, in general the whole system looks confusing to me.