可以把 QML 类型导入应用程序，使用以下 import 语句在 .qml 文件：
import QtQuick.VirtualKeyboard.Styles 2.2
| KeyIcon | 具有可调节颜色的键图标 |
| KeyPanel | A base type of the styled keys |
| KeyboardStyle | Provides a styling interface for the Virtual Keyboard |
| SelectionListItem | A base type for selection list item delegates |
| TraceCanvas | A specialized Canvas type for rendering Trace objects |
| TraceInputKeyPanel | 跟踪输入键的基类型 |
