### Godot version

4.0.beta12

### System information

Windows 11, RTX 3080

### Issue description

When a Window Node is created with it's Transparent flag set to true and Project Settings --> Display --> Window --> Subwindows --> Embed Subwindows is false, the Window has a black background. By cycling the transparent flag from false and back to true again, during runtime, the window's background then becomes transparent. 

### Steps to reproduce

Attempt to create a Non-embedded Subwindow with a transparent background using the appropriate flags. 

### Minimal reproduction project

Note: this project is from Reddit user [gongpha](https://www.reddit.com/user/gongpha/) and his Reddit post [Learning a Godot 4.0 Window node](https://www.reddit.com/r/godot/comments/xr8yxn/learning_a_godot_40_window_node/)

https://github.com/gongpha/godot4-window-test
}
						prev_wck = unicode;
						break; 
					} else if ((unicode & 0xfffffc00) == 0xdc00) {
						if (prev_wck == 0) {
							ERR_PRINT("invalid utf16 surrogate input");
							break; 
						}
						unicode = (prev_wck << 10UL) + unicode - ((0xd800 << 10UL) + 0xdc00 - 0x10000);
						prev_wck = 0;
					} else {
						prev_wck = 0;
					}
					k->set_unicode(unicode);
				}
				if (k->get_unicode() && gr_mem) {
					k->set_alt_pressed(false);
					k->set_ctrl_pressed(false);
				}
				if (k->get_unicode() < 32) {
					k->set_unicode(0);
				}
				k->set_echo((ke.uMsg == WM_KEYDOWN && (ke.lParam & (1 << 30))));
				Input::get_singleton()->parse_input_event(k);
			} break;
		}
	}
	key_event_pos = 0;
}
void DisplayServerWindows::_update_tablet_ctx(const String &p_old_driver, const String &p_new_driver) {