### 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_NULL(wrapped_control);
	if (!is_window_available()) {
		return;
	}
	if (window->is_visible() == p_visible) {
		if (p_visible) {
			window->grab_focus();
		}
		return;
	}
	Node *parent = _get_wrapped_control_parent();
	if (wrapped_control->get_parent() != parent) {
		
		wrapped_control->reparent(parent, false);
		_set_window_rect(p_rect);
		wrapped_control->set_anchors_and_offsets_preset(PRESET_FULL_RECT);
	} else if (!p_visible) {
		
		wrapped_control->reparent(this, false);
	}
	window->set_visible(p_visible);
	if (!p_visible) {
		emit_signal("window_close_requested");
	}
	emit_signal("window_visibility_changed", p_visible);
}
void WindowWrapper::_set_window_rect(const Rect2 p_rect) {