Perhaps it’s too late for suggestions, or perhaps this is not the right forum for it, but there is something that annoys me, and I think it’s easy to solve.

In daytime I use the solarized light theme, and in the evening solarized dark. What annoys me is that I first have to open Scrivener before I can change it. Then to restart Scrivener it usually fully saves the project before closing, which slows the process down even more. I was thinking this could be solved with a tiny launcher, that’s similar to the pop-up notifying the beta expiration date we have now. In the mini-launcher perhaps I could select the theme, and also select which project to work on, from a list of most recent ones. Maybe the launcher should be optional, in case many people don’t need it.

Just a small idea, for a small nuisance of mine.

If you close the project before closing Scrivener, doesn’t it start empty?
There should also be a setting in Tools -> Options where you can specify if Scrivener should automatically re-open the project you had open on close. Un-toggle this and you have what you want.

Win Scrivener is said to get “feature parity” and the Mac version starts like this when no project is open. There you also have the list of recently opened projects at the bottom:

I know that, and actually I added the Scrivener icon to the taskbar, and if I right-click on it, I can select from recent projects too. The main issue is theme selection for me. Saving my (large) project takes 10 seconds, so switching theme is a bit of a hassle (a very small one, I admit).

Saving is done automatically in the background, all the time.
Is it the creation of backups that take 10 sec?

Yes, it’s the backup that takes 10 seconds. I find it very convenient that it creates the backup, so to disable that wouldn’t be a good solution.

If you close the project before leaving the Mac, you make it create a backup and Scrivener opens empty. Problem solved.

Hopefully they get the core problem fixed some day, where themes do not require a restart to switch. I think it may be a limitation of the framework being used, however. In the meanwhile, I’d consider leaving a copy of the tutorial hanging around, or even just a simple blank project—either of which can have the backup option disabled (see Project ▸ Project Settings…), then use that to double-click on so you have something to switch themes with other than you main project.