Godot code for getting mouse and keyboard input while window is not focused

GlobalInput.cs

using Godot;
using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;

public class GlobalInput : Godot.Node
{

	private Dictionary<int, string> keyWatches = new Dictionary<int, string>();
	private Dictionary<int, bool> keyStates = new Dictionary<int, bool>();

	[Signal]
	delegate void key_event(string key, bool pressed);

	public override void _Process(float delta) {
		foreach (int keyCode in keyWatches.Keys) {
			bool state = IsKeyPressed(keyCode);
			if (state != keyStates[keyCode]) {
				keyStates[keyCode] = state;
				EmitSignal("key_event", keyWatches[keyCode], state);
			}
		}
	}

	public void watch_key_raw(int key_code, string key_name) {
		if (!keyWatches.ContainsKey(key_code)) {
			keyWatches.Add(key_code, key_name);
			keyStates.Add(key_code, false);
		}
	}

	public Vector2 get_mouse_position() {
		return GetCursorPosition();
	}

	public bool is_mouse_button_pressed(int button_index) {
		if (!buttonMap.ContainsKey(button_index)) return false;
		return IsKeyPressed(buttonMap[button_index]);
	}

	public bool is_key_pressed(int scancode) {
		return false;
	}

	public bool is_key_pressed_raw(int key_code) {
		return IsKeyPressed(key_code);
		// https://docs.microsoft.com/en-us/windows/win32/inputdev/virtual-key-codes
	}

	static Dictionary<int, int> buttonMap = new Dictionary<int, int>() {
		{(int)ButtonList.Left, 0x1},
		{(int)ButtonList.Right, 0x2},
		{(int)ButtonList.Middle, 0x4},
		{(int)ButtonList.Xbutton1, 0x5},
		{(int)ButtonList.Xbutton2, 0x6}
	};

	[StructLayout(LayoutKind.Sequential)]
	public struct POINT
	{
		public int X;
		public int Y;

		public static implicit operator Vector2(POINT point)
		{
			return new Vector2(point.X, point.Y);
		}
	}

	[DllImport("user32.dll")]
	public static extern bool GetCursorPos(out POINT lpPoint);
	[DllImport("user32.dll")]
	public static extern short GetAsyncKeyState(UInt16 virtualKeyCode);

	public static Vector2 GetCursorPosition()
	{
		POINT lpPoint;
		GetCursorPos(out lpPoint);
		return lpPoint;
	}

	public static bool IsKeyPressed(int code) {
		return GetAsyncKeyState((UInt16)code) != 0;
	}

	// Source: https://stackoverflow.com/questions/1316681/getting-mouse-position-in-c-sharp

}

UsageExample.gd

extends Node

# This is used by setting the GlobalInput C# script as a singleton

func _ready():
	GlobalInput.watch_key_raw(0xA0, "shift_left")
	GlobalInput.connect("key_event", self, "_on_key")

func _process(delta: float) -> void:
	$Label.text = var2str(GlobalInput.get_mouse_position())
	$Label2.text = "yes" if GlobalInput.is_mouse_button_pressed(BUTTON_LEFT) else "no"
	
	var shift = GlobalInput.is_key_pressed_raw(0x10)
	var left_shift = GlobalInput.is_key_pressed_raw(0xA0)
	var right_shift = GlobalInput.is_key_pressed_raw(0xA1)
	
	$Label3.text = ("yes " if shift else "no ") + ("left" if left_shift else "") + ("right" if right_shift else "")

func _on_key(key, pressed):
	print("KEY! ", key, pressed)