### 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
EditorPlugin::AfterGUIInput after = EditorPlugin::AFTER_GUI_INPUT_PASS;
	for (int i = 0; i < plugins_list.size(); i++) {
		if ((!serve_when_force_input_enabled) && plugins_list[i]->is_input_event_forwarding_always_enabled()) {
			continue;
		}
		EditorPlugin::AfterGUIInput current_after = plugins_list[i]->forward_3d_gui_input(p_camera, p_event);
		if (current_after == EditorPlugin::AFTER_GUI_INPUT_STOP) {
			after = EditorPlugin::AFTER_GUI_INPUT_STOP;
		}
		if (after != EditorPlugin::AFTER_GUI_INPUT_STOP && current_after == EditorPlugin::AFTER_GUI_INPUT_CUSTOM) {
			after = EditorPlugin::AFTER_GUI_INPUT_CUSTOM;
		}
	}
	return after;
}
void EditorPluginList::forward_canvas_draw_over_viewport(Control *p_overlay) {
	for (int i = 0; i < plugins_list.size(); i++) {
		plugins_list[i]->forward_canvas_draw_over_viewport(p_overlay);
	}
}
void EditorPluginList::forward_canvas_force_draw_over_viewport(Control *p_overlay) {
	for (int i = 0; i < plugins_list.size(); i++) {
		plugins_list[i]->forward_canvas_force_draw_over_viewport(p_overlay);
	}
}
void EditorPluginList::forward_3d_draw_over_viewport(Control *p_overlay) {