### 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
main_editor_buttons[EDITOR_SCRIPT]->set_visible(true);
		if (AssetLibraryEditorPlugin::is_available()) {
			main_editor_buttons[EDITOR_ASSETLIB]->set_visible(true);
		}
	}
	_update_dock_slots_visibility();
}
void EditorNode::_bind_methods() {
	ClassDB::bind_method("edit_current", &EditorNode::edit_current);
	ClassDB::bind_method("edit_node", &EditorNode::edit_node);
	ClassDB::bind_method(D_METHOD("push_item", "object", "property", "inspector_only"), &EditorNode::push_item, DEFVAL(""), DEFVAL(false));
	ClassDB::bind_method("set_edited_scene", &EditorNode::set_edited_scene);
	ClassDB::bind_method("open_request", &EditorNode::open_request);
	ClassDB::bind_method("edit_foreign_resource", &EditorNode::edit_foreign_resource);
	ClassDB::bind_method("is_resource_read_only", &EditorNode::is_resource_read_only);
	ClassDB::bind_method("stop_child_process", &EditorNode::stop_child_process);
	ClassDB::bind_method("set_current_scene", &EditorNode::set_current_scene);
	ClassDB::bind_method("_thumbnail_done", &EditorNode::_thumbnail_done);
	ClassDB::bind_method("_set_main_scene_state", &EditorNode::_set_main_scene_state);
	ClassDB::bind_method("_update_recent_scenes", &EditorNode::_update_recent_scenes);
	ClassDB::bind_method(D_METHOD("get_gui_base"), &EditorNode::get_gui_base);
	ADD_SIGNAL(MethodInfo("request_help_search"));
	ADD_SIGNAL(MethodInfo("script_add_function_request", PropertyInfo(Variant::OBJECT, "obj"), PropertyInfo(Variant::STRING, "function"), PropertyInfo(Variant::PACKED_STRING_ARRAY, "args")));
	ADD_SIGNAL(MethodInfo("resource_saved", PropertyInfo(Variant::OBJECT, "obj")));
	ADD_SIGNAL(MethodInfo("scene_saved", PropertyInfo(Variant::STRING, "path")));
	ADD_SIGNAL(MethodInfo("project_settings_changed"));
	ADD_SIGNAL(MethodInfo("scene_changed"));
	ADD_SIGNAL(MethodInfo("scene_closed", PropertyInfo(Variant::STRING, "path")));
}
static Node *_resource_get_edited_scene() {