### 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
Ref<InputEventMouseButton> mb = p_input;
	if (mb.is_valid()) {
		if (scene_tabs->get_hovered_tab() >= 0) {
			if (mb->get_button_index() == MouseButton::MIDDLE && mb->is_pressed()) {
				_scene_tab_closed(scene_tabs->get_hovered_tab());
			}
		} else {
			if (mb->get_button_index() == MouseButton::LEFT && mb->is_double_click()) {
				_menu_option_confirm(FILE_NEW_SCENE, true);
			}
		}
		if (mb->get_button_index() == MouseButton::RIGHT && mb->is_pressed()) {
			
			scene_tabs_context_menu->clear();
			scene_tabs_context_menu->reset_size();
			scene_tabs_context_menu->add_shortcut(ED_GET_SHORTCUT("editor/new_scene"), FILE_NEW_SCENE);
			if (scene_tabs->get_hovered_tab() >= 0) {
				scene_tabs_context_menu->add_shortcut(ED_GET_SHORTCUT("editor/save_scene"), FILE_SAVE_SCENE);
				scene_tabs_context_menu->add_shortcut(ED_GET_SHORTCUT("editor/save_scene_as"), FILE_SAVE_AS_SCENE);
			}
			scene_tabs_context_menu->add_shortcut(ED_GET_SHORTCUT("editor/save_all_scenes"), FILE_SAVE_ALL_SCENES);
			if (scene_tabs->get_hovered_tab() >= 0) {
				scene_tabs_context_menu->add_separator();
				scene_tabs_context_menu->add_item(TTR("Show in FileSystem"), FILE_SHOW_IN_FILESYSTEM);
				scene_tabs_context_menu->add_item(TTR("Play This Scene"), FILE_RUN_SCENE);
				scene_tabs_context_menu->add_separator();
				scene_tabs_context_menu->add_shortcut(ED_GET_SHORTCUT("editor/close_scene"), FILE_CLOSE);
				scene_tabs_context_menu->set_item_text(scene_tabs_context_menu->get_item_index(FILE_CLOSE), TTR("Close Tab"));