标签myItemContent =新标签（我的内容）; 
 myItemContent.addMouseOverHandler（new MouseOverHandler（）{
 $ b $ public void onMouseOver（MouseOverEvent event）{
 //构造和/或打开您的工具提示
} 
}）; 

 myItemContent.addMouseOutHandler（new MouseOutHandler（）{

 public void onMouseOut（MouseOutEvent event）{
 //关闭您的工具提示

 } 
}）; 
 //将您的Label放入TreeItem中
 TreeItem myItem = new TreeItem（myItemContent）; 
 //假设parentNode是一个ItemTree 
 parentNode.addItem（myItem）; 
 

另一个解决方案是使用GwtQuery。 GwtQuery允许将事件处理程序绑定到任何DOM元素：

  import static com.google.gwt.query.client.GQuery。$ ; 

 ... 

 TreeItem myItem = new TreeItem（My content）; 
 $（myItem.getElement（））。hover（new Function（）{

 //在鼠标上调用的方法超过
 public void f（Element e）{
 //构造和/或打开你的工具提示
} 

}，new Function（）{

 //在鼠标上调用的方法
 public void f（Element e）{
 //关闭您的工具提示
} 
}）; 

 parentNode.addItem（myItem）; 
 

Julien

I'm trying to add tooltips for the nodes of a Tree in GWT. As such, I'd like to add a mouseover listener for the nodes of a tree rather than on the tree itself.

The Treelistener interface seems to be what I want but this is now deprecated in lieu of the handler system. I don't quite understand how to get mouseover behaviour on the cell as I only seem to be able to add a MouseOverHandler to the tree itself.

Any help would be appreciated, thank you.

A TreeItem can contains a Widget object. So add a MouseOverHandler and a MouseOutHandler on a widget (i.e. a Label) and put the widget inside the TreeItem to add :

Label myItemContent = new Label("My content");
myItemContent.addMouseOverHandler(new MouseOverHandler() {

  public void onMouseOver(MouseOverEvent event) {
    // construct and/or open your tooltip
  }
});

myItemContent.addMouseOutHandler(new MouseOutHandler() {

  public void onMouseOut(MouseOutEvent event) {
    // close your tooltip

  }
});
//put your Label inside a TreeItem
TreeItem myItem = new TreeItem(myItemContent);
// let's assume that parentNode is an ItemTree
parentNode.addItem(myItem);

An other solution can be to use GwtQuery. GwtQuery allows to bind event handler to any DOM element :

import static com.google.gwt.query.client.GQuery.$;

...

TreeItem myItem = new TreeItem("My content");
$(myItem.getElement()).hover(new Function() {

  //method called on mouse over
  public void f(Element e) {
      // construct and/or open your tooltip
  }

}, new Function() {

  //method called on mouse out
  public void f(Element e) {
      //close your tooltip
  }
});

parentNode.addItem(myItem);

Julien