What does a blue color on the scene filename mean?

Question

I encountered this behaviour when reorganising my project (Renaming, and moving); though I'm not sure as to what exactly caused it:

For some reason, the filename of one of my scenes has turned blue. It doesn't really create any problems, or change anything, really, but it's odd; it's persistent, so it probably means something, but since there's no tooltip that I can find, I have no idea what that could be.

Answer 1

I'm not sure, but it looks like it highlights the main scene defined in your project settings. I tried to change it to check, and it did not update. But when I restarted my project, the new main scene was blue.

Confirmed in source code: https://github.com/godotengine/godot/blob/4f5ad0734b588f223aa78193b60620d7490e633b/editor/filesystem_dock.cpp#L124