### 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
ERR_FAIL_COND(plugin_init_callback_count == MAX_INIT_CALLBACKS);
	plugin_init_callbacks[plugin_init_callback_count++] = p_callback;
}
EditorPluginInitializeCallback EditorNode::plugin_init_callbacks[EditorNode::MAX_INIT_CALLBACKS];
int EditorNode::build_callback_count = 0;
void EditorNode::add_build_callback(EditorBuildCallback p_callback) {
	ERR_FAIL_COND(build_callback_count == MAX_INIT_CALLBACKS);
	build_callbacks[build_callback_count++] = p_callback;
}
EditorBuildCallback EditorNode::build_callbacks[EditorNode::MAX_BUILD_CALLBACKS];
bool EditorNode::call_build() {
	bool builds_successful = true;
	for (int i = 0; i < build_callback_count && builds_successful; i++) {
		if (!build_callbacks[i]()) {
			ERR_PRINT("A Godot Engine build callback failed.");
			builds_successful = false;
		}
	}
	if (builds_successful && !editor_data.call_build()) {
		ERR_PRINT("An EditorPlugin build callback failed.");
		builds_successful = false;
	}
	return builds_successful;
}
void EditorNode::_inherit_imported(const String &p_action) {