### 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
open_imported->hide();
	load_scene(open_import_request, true, true);
}
void EditorNode::_open_imported() {
	load_scene(open_import_request, true, false, true, true);
}
void EditorNode::dim_editor(bool p_dimming) {
	dimmed = p_dimming;
	gui_base->set_modulate(p_dimming ? Color(0.5, 0.5, 0.5) : Color(1, 1, 1));
}
bool EditorNode::is_editor_dimmed() const {
	return dimmed;
}
void EditorNode::open_export_template_manager() {
	export_template_manager->popup_manager();
}
void EditorNode::add_resource_conversion_plugin(const Ref<EditorResourceConversionPlugin> &p_plugin) {