AltGr button does not work correctly on QWERTZ keyboard

[gitsomebit]

Tested versions

• Reproducable in 4.3 stable and 4.2 stable

System information

Windows 10 - Godot 4.3 - Compatibility - QWERTZ keyboard

Issue description

I am working on a input remapping system for my game.
As you know when AltGr is pressed together with another key, the key should have the modifiers of Ctrl and Alt.
This is not the case for all keys as it works for some and for some it does not.

Steps to reproduce

create a new scene with a control node and use the _input() function:

func _input(event: InputEvent) -> void:
	if event is InputEventKey and event.pressed and not event.is_echo():
		match event.physical_keycode:
			KEY_CTRL, KEY_SHIFT:
				pass
			_:
				print(event)

When holding down AltGr and pressing the toprow number keys one after another produces the following results (some have mods, some dont):

InputEventKey: keycode=4194328 (Alt), mods=Ctrl, physical=false, location=right, pressed=true, echo=false
InputEventKey: keycode=49 (1), mods=Ctrl+Alt, physical=false, location=unspecified, pressed=true, echo=false
InputEventKey: keycode=50 (2), mods=none, physical=false, location=unspecified, pressed=true, echo=false
InputEventKey: keycode=51 (3), mods=none, physical=false, location=unspecified, pressed=true, echo=false
InputEventKey: keycode=52 (4), mods=Ctrl+Alt, physical=false, location=unspecified, pressed=true, echo=false
InputEventKey: keycode=53 (5), mods=Ctrl+Alt, physical=false, location=unspecified, pressed=true, echo=false
InputEventKey: keycode=54 (6), mods=Ctrl+Alt, physical=false, location=unspecified, pressed=true, echo=false
InputEventKey: keycode=55 (7), mods=none, physical=false, location=unspecified, pressed=true, echo=false
InputEventKey: keycode=56 (8), mods=none, physical=false, location=unspecified, pressed=true, echo=false
InputEventKey: keycode=57 (9), mods=none, physical=false, location=unspecified, pressed=true, echo=false
InputEventKey: keycode=48 (0), mods=none, physical=false, location=unspecified, pressed=true, echo=false
InputEventKey: keycode=91 (BracketLeft), mods=none, physical=false, location=unspecified, pressed=true, echo=false
InputEventKey: keycode=93 (BracketRight), mods=Ctrl+Alt, physical=false, location=unspecified, pressed=true, echo=false

Minimal reproduction project (MRP)

MRP_Godot-4.3: AltGr_Bug.zip

[gitsomebit]

QWERTZ keyboard layout:

[bruvzg]

As you know when AltGr is pressed together with another key, the key should have the modifiers of Ctrl and Alt.

Ctrl+Alt can be used as substitute for AltGr (on Windows), not sure if reverse should be always true.

The keys that do not have modifiers set seems to keys with associated third level character values (blue), so it's likely cause by processing characters:

[bruvzg]

We actually deliberately unset modifiers for key events like this:

godot/platform/windows/display_server_windows.cpp

Lines 5441 to 5444 in 87318a2

	if (k->get_unicode() && ke.altgr) {
	k->set_alt_pressed(false);
	k->set_ctrl_pressed(false);
	}

It was like added in #189, before proper IME support, and might unnecessary (or at least can be only enabled while text input mode is active).