### Godot version

v4.2.dev.custom_build [0c2144da9]

### System information

Debian Linux X11 Xfce

### Issue description

Prerequisite: Be in Single Window Mode in the Editor
The Filesystem Dock is unusable when it is floating, which is not expected.
It appears garbled in the top-left corner:
![image](https://github.com/godotengine/godot/assets/6299227/109f7922-97de-44c3-814a-ca7f970e0602)

The following errors are shown:
```
  editor/window_wrapper.cpp:220 - Condition "!is_window_available()" is true.
  editor/window_wrapper.cpp:202 - Condition "!get_window_enabled()" is true. Returning: Rect2i()
  editor/window_wrapper.cpp:207 - Condition "!get_window_enabled()" is true. Returning: -1
  editor/window_wrapper.cpp:207 - Condition "!get_window_enabled()" is true. Returning: -1
```

bisecting lead to #62378
possibly related to #44439

### Steps to reproduce

1. Start a project in the Editor
2. Switch to Single Window Mode in the Editor and reload (if necessary)
3. Make the Filesystem Dock floating

### Minimal reproduction project

Editor issue
ED_SHORTCUT_AND_COMMAND("editor/editor_2d", TTR("Open 2D Editor"), KeyModifierMask::CTRL | Key::F1);
	ED_SHORTCUT_AND_COMMAND("editor/editor_3d", TTR("Open 3D Editor"), KeyModifierMask::CTRL | Key::F2);
	ED_SHORTCUT_AND_COMMAND("editor/editor_script", TTR("Open Script Editor"), KeyModifierMask::CTRL | Key::F3);
	ED_SHORTCUT_AND_COMMAND("editor/editor_assetlib", TTR("Open Asset Library"), KeyModifierMask::CTRL | Key::F4);
	ED_SHORTCUT_OVERRIDE("editor/editor_2d", "macos", KeyModifierMask::META | KeyModifierMask::CTRL | Key::KEY_1);
	ED_SHORTCUT_OVERRIDE("editor/editor_3d", "macos", KeyModifierMask::META | KeyModifierMask::CTRL | Key::KEY_2);
	ED_SHORTCUT_OVERRIDE("editor/editor_script", "macos", KeyModifierMask::META | KeyModifierMask::CTRL | Key::KEY_3);
	ED_SHORTCUT_OVERRIDE("editor/editor_assetlib", "macos", KeyModifierMask::META | KeyModifierMask::CTRL | Key::KEY_4);
	ED_SHORTCUT_AND_COMMAND("editor/editor_next", TTR("Open the next Editor"));
	ED_SHORTCUT_AND_COMMAND("editor/editor_prev", TTR("Open the previous Editor"));
	screenshot_timer = memnew(Timer);
	screenshot_timer->set_one_shot(true);
	screenshot_timer->set_wait_time(settings_menu->get_submenu_popup_delay() + 0.1f);
	screenshot_timer->connect("timeout", callable_mp(this, &EditorNode::_request_screenshot));
	add_child(screenshot_timer);
	screenshot_timer->set_owner(get_owner());
	
	int max_w = MAX(project_run_bar->get_minimum_size().x + right_menu_hb->get_minimum_size().x, main_menu->get_minimum_size().x);
	left_spacer->set_custom_minimum_size(Size2(MAX(0, max_w - main_menu->get_minimum_size().x), 0));
	right_spacer->set_custom_minimum_size(Size2(MAX(0, max_w - project_run_bar->get_minimum_size().x - right_menu_hb->get_minimum_size().x), 0));
	
	if (can_expand) {
		DisplayServer::get_singleton()->window_set_flag(DisplayServer::WINDOW_FLAG_EXTEND_TO_TITLE, true, DisplayServer::MAIN_WINDOW_ID);
		title_bar->set_can_move_window(true);
	}
	String exec = OS::get_singleton()->get_executable_path();
	
	EditorSettings::get_singleton()->set_project_metadata("editor_metadata", "executable_path", exec);
}
EditorNode::~EditorNode() {