### 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
scene_tabs->set_current_tab(p_tab);
}
void EditorNode::_update_layouts_menu() {
	editor_layouts->clear();
	overridden_default_layout = -1;
	editor_layouts->reset_size();
	editor_layouts->add_shortcut(ED_SHORTCUT("layout/save", TTR("Save Layout")), SETTINGS_LAYOUT_SAVE);
	editor_layouts->add_shortcut(ED_SHORTCUT("layout/delete", TTR("Delete Layout")), SETTINGS_LAYOUT_DELETE);
	editor_layouts->add_separator();
	editor_layouts->add_shortcut(ED_SHORTCUT("layout/default", TTR("Default")), SETTINGS_LAYOUT_DEFAULT);
	Ref<ConfigFile> config;
	config.instantiate();
	Error err = config->load(EditorSettings::get_singleton()->get_editor_layouts_config());
	if (err != OK) {
		return; 
	}
	List<String> layouts;
	config.ptr()->get_sections(&layouts);
	for (const String &layout : layouts) {
		if (layout == TTR("Default")) {
			editor_layouts->remove_item(editor_layouts->get_item_index(SETTINGS_LAYOUT_DEFAULT));
			overridden_default_layout = editor_layouts->get_item_count();
		}
		editor_layouts->add_item(layout);
	}
}
void EditorNode::_layout_menu_option(int p_id) {
	switch (p_id) {
		case SETTINGS_LAYOUT_SAVE: {