### 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
HashMap<NodePath, ModificationNodeEntry> modification_table;
				List<AdditiveNodeEntry> addition_list;
				update_diff_data_for_node(current_edited_scene, original_node, original_node, modification_table, addition_list);
				
				for (const KeyValue<NodePath, ModificationNodeEntry> &modification_table_entry : modification_table) {
					for (Connection conn : modification_table_entry.value.connections_from) {
						conn.signal.get_object()->disconnect(conn.signal.get_name(), conn.callable);
					}
					for (ConnectionWithNodePath cwnp : modification_table_entry.value.connections_to) {
						Connection conn = cwnp.connection;
						if (conn.flags & CONNECT_PERSIST) {
							conn.signal.get_object()->disconnect(conn.signal.get_name(), conn.callable);
						}
					}
				}
				
				List<NodePath> selected_node_paths;
				for (Node *selected_node : editor_selection->get_selected_node_list()) {
					if (selected_node == original_node || original_node->is_ancestor_of(selected_node)) {
						selected_node_paths.push_back(original_node->get_path_to(selected_node));
						editor_selection->remove_node(selected_node);
					}
				}
				
				for (AdditiveNodeEntry additive_node_entry : addition_list) {
					Node *addition_node = additive_node_entry.node;
					addition_node->get_parent()->remove_child(addition_node);
				}