GWT弹出式面板是透明的？

Question

我正在使用Gwt，

我有一个标签。在onClick事件中有一个​​，增加了tree。 问题是popupPanel是透明的。

当执行popup.show时，通过popupPanel看到popupPanel后面的panel。如何避免这一点。

. 
    . 
     lblClass.addClickHandler(new ClickHandler() { 
         public void onClick(ClickEvent event) { 
          getPopupPanel(); 
         } 
        }); 
private PopupPanel getPopupPanel(){ 

      popupPanel = new PopupPanel(); 
      popupPanel.setStyleName("documentClass-PopPup"); 
      int x =lblClass.getAbsoluteLeft(); 
      int y = lblClass.getAbsoluteTop(); 
      popupPanel.setPopupPosition(x, y+20); 
      popupPanel.add(getCustomPropertiesTree()); 
      popupPanel.show(); 

     return popupPanel; 
    } 

CSS 

.documentClass-PopPup { 
    margin: 2px 1px 1px; 
    padding: 2px 1px 1px; 
    border-top: thick; 
    border-right: medium; 
    border-bottom: medium; 
    border-left: medium; 
    font-size: 10pt; 
    letter-spacing: normal; 

} 

Answer 1

要么定义背景色 “的DocumentClass，弹出”

.documentClass-PopPup { 
    background-color: white; 
} 

或者使用

popupPanel.addStyleName("documentClass-PopPup"); 

，而不是

popupPanel.setStyleName("documentClass-PopPup");