### 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
file_menu->add_shortcut(ED_SHORTCUT_AND_COMMAND("editor/new_scene", TTR("New Scene"), KeyModifierMask::CMD_OR_CTRL + Key::N), FILE_NEW_SCENE);
	file_menu->add_shortcut(ED_SHORTCUT_AND_COMMAND("editor/new_inherited_scene", TTR("New Inherited Scene..."), KeyModifierMask::CMD_OR_CTRL + KeyModifierMask::SHIFT + Key::N), FILE_NEW_INHERITED_SCENE);
	file_menu->add_shortcut(ED_SHORTCUT_AND_COMMAND("editor/open_scene", TTR("Open Scene..."), KeyModifierMask::CMD_OR_CTRL + Key::O), FILE_OPEN_SCENE);
	file_menu->add_shortcut(ED_SHORTCUT_AND_COMMAND("editor/reopen_closed_scene", TTR("Reopen Closed Scene"), KeyModifierMask::CMD_OR_CTRL + KeyModifierMask::SHIFT + Key::T), FILE_OPEN_PREV);
	file_menu->add_submenu_item(TTR("Open Recent"), "RecentScenes", FILE_OPEN_RECENT);
	file_menu->add_separator();
	file_menu->add_shortcut(ED_SHORTCUT_AND_COMMAND("editor/save_scene", TTR("Save Scene"), KeyModifierMask::CMD_OR_CTRL + Key::S), FILE_SAVE_SCENE);
	file_menu->add_shortcut(ED_SHORTCUT_AND_COMMAND("editor/save_scene_as", TTR("Save Scene As..."), KeyModifierMask::CMD_OR_CTRL + KeyModifierMask::SHIFT + Key::S), FILE_SAVE_AS_SCENE);
	file_menu->add_shortcut(ED_SHORTCUT_AND_COMMAND("editor/save_all_scenes", TTR("Save All Scenes"), KeyModifierMask::CMD_OR_CTRL + KeyModifierMask::SHIFT + KeyModifierMask::ALT + Key::S), FILE_SAVE_ALL_SCENES);
	file_menu->add_separator();
	file_menu->add_shortcut(ED_SHORTCUT_AND_COMMAND("editor/quick_open", TTR("Quick Open..."), KeyModifierMask::SHIFT + KeyModifierMask::ALT + Key::O), FILE_QUICK_OPEN);
	ED_SHORTCUT_OVERRIDE("editor/quick_open", "macos", KeyModifierMask::META + KeyModifierMask::CTRL + Key::O);
	file_menu->add_shortcut(ED_SHORTCUT_AND_COMMAND("editor/quick_open_scene", TTR("Quick Open Scene..."), KeyModifierMask::CMD_OR_CTRL + KeyModifierMask::SHIFT + Key::O), FILE_QUICK_OPEN_SCENE);
	file_menu->add_shortcut(ED_SHORTCUT_AND_COMMAND("editor/quick_open_script", TTR("Quick Open Script..."), KeyModifierMask::CMD_OR_CTRL + KeyModifierMask::ALT + Key::O), FILE_QUICK_OPEN_SCRIPT);
	file_menu->add_separator();
	export_as_menu = memnew(PopupMenu);
	export_as_menu->set_name("Export");
	file_menu->add_child(export_as_menu);
	file_menu->add_submenu_item(TTR("Export As..."), "Export");
	export_as_menu->add_shortcut(ED_SHORTCUT("editor/export_as_mesh_library", TTR("MeshLibrary...")), FILE_EXPORT_MESH_LIBRARY);
	export_as_menu->connect("index_pressed", callable_mp(this, &EditorNode::_export_as_menu_option));
	file_menu->add_separator();
	file_menu->add_shortcut(ED_GET_SHORTCUT("ui_undo"), EDIT_UNDO, true);
	file_menu->add_shortcut(ED_GET_SHORTCUT("ui_redo"), EDIT_REDO, true);
	file_menu->add_separator();
	file_menu->add_shortcut(ED_SHORTCUT_AND_COMMAND("editor/reload_saved_scene", TTR("Reload Saved Scene")), EDIT_RELOAD_SAVED_SCENE);
	file_menu->add_shortcut(ED_SHORTCUT_AND_COMMAND("editor/close_scene", TTR("Close Scene"), KeyModifierMask::CMD_OR_CTRL + KeyModifierMask::SHIFT + Key::W), FILE_CLOSE);
	recent_scenes = memnew(PopupMenu);
	recent_scenes->set_name("RecentScenes");
	file_menu->add_child(recent_scenes);