FocusAgent
From Documentation
It's supported on those components that inherit org.zkoss.zul.impl.InputElement
```java
inputComponent.as(FocusAgent.class).focus();
inputComponent.as(FocusAgent.class).blur();
```
It's supported on those components that inherit org.zkoss.zul.impl.InputElement
```java
inputComponent.as(FocusAgent.class).focus();
inputComponent.as(FocusAgent.class).blur();
```