### 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
scene_tabs->set_current_tab(cur_idx);
		} break;
		case FILE_SHOW_IN_FILESYSTEM: {
			String path = editor_data.get_scene_path(editor_data.get_edited_scene());
			if (!path.is_empty()) {
				FileSystemDock::get_singleton()->navigate_to_path(path);
			}
		} break;
		case RUN_SETTINGS: {
			project_settings_editor->popup_project_settings();
		} break;
		case FILE_INSTALL_ANDROID_SOURCE: {
			if (p_confirmed) {
				export_template_manager->install_android_template();
			} else {
				if (DirAccess::exists("res:android/build")) {
					remove_android_build_template->popup_centered();
				} else if (export_template_manager->can_install_android_template()) {
					install_android_build_template->popup_centered();
				} else {
					gradle_build_manage_templates->popup_centered();
				}
			}
		} break;
		case TOOLS_BUILD_PROFILE_MANAGER: {
			build_profile_manager->popup_centered_clamped(Size2(700, 800) * EDSCALE, 0.8);
		} break;
		case RUN_USER_DATA_FOLDER: {
			
			OS::get_singleton()->ensure_user_data_dir();