Properly expose Immersive Mode on android

[syntaxerror247]

For a long time, I wasn't aware that Android had a runtime method to toggle immersive mode. It wasn't until a few days ago, when I started working on this proposal, that I discovered it could already be done using window_set_mode.

I have two potential solutions now:

1. Update the documentation to clarify that immersive mode is activated when either WINDOW_MODE_EXCLUSIVE_FULLSCREEN or WINDOW_MODE_FULLSCREEN is set.
2. Introduce a new method in DisplayServer. We could keep window_set_mode as it is and add a dedicated toggle_immersive_mode() function for better clarity and control.

Let me know which solution you think is better :)

[m4gr3d]

Let's go with the first approach!
The use of window_set_mode also provides us with added flexibility given that pure immersive mode is not available on all platforms.

[syntaxerror247]

@m4gr3d Ok, so if we are going with first approach, then I would like to add a note in android export Immersive mode toggle description : "See window_set_mode to toggle it at runtime".

[m4gr3d]

Yeah, that's a good idea! I was debating removing or at least renaming that export setting because the ability to do so at runtime should supercede it.
The only advantage of that setting now is to activate fullscreen before the game logic is able to run.

[syntaxerror247]

I am not sure if removing would be a good idea because games mostly use immersive mode and setting it during build is better.
But yeah renaming should be considered.