1. run NetBeans IDE 6.0 Preview M9
2. create a JPane Form named "NewJPane1" in a project, then it was showed in 
Matisse GUI Builder, and Inspector window show a object tree on NewJPanel
3. right click the node of "Other Components" in the Inspector window, select 
the menu "Add From Palette->Swing Menus->Popup Menu"
4. right click the node of 'jPopupMenu1' under "Other Components" in the 
Inspector window, the menu item "Add From Palette" and "Change Order..." are 
disappear, so we can't add a new JMenuItem to a JPopupMenu.
5. The result is:
You can insert a new JMenuItem into an existent JPopupMenu in a NetBeans5.5's 
project under NetBeans6.0M9.
But you can't insert a new JMenuItem into a new JPopupMenu in NetBeans5.5's or 
NetBeans6.0M9's project under NetBeans6.0M9.
The menu item "Add From Palette" and "Change Order..." are disappear when right 
click a new JPopupMenu under NetBeans6.0M9.

Chinese:
1. 运行NetBeans IDE 6.0M9
2. 在项目中创建一个名为“NewJPane1”的面板，于是他显示在Matisse的GUI生成器窗口中，同时，
在左下方的检查器窗口中显示了NewJPane1的对象树
3. 在检查器窗口的“其他组件”节点上按鼠标右键，选择菜单“从组件面板上添加->Swing Menus-
>Popup Menu”
4. 在检查器窗口的“其他组件”的下级节点“jPopupMenu1”上按鼠标右键，此选择菜单中没有“添
加”和“更改顺序”这两个子菜单了，因此，我们无法把JMenuItem添加到JPopupMenu里
5. 结论是：
在NetBeans6.0M9中，你可以打开一个NetBeans5.5的项目，并向已经存在的JPopupMenu中添加菜单
项JMenuItem。
但是，在NetBeans6.0M9中，无论打开一个NetBeans5.5的项目还是打开一个NetBeans6.0M9的项
目，都无法向一个新的JPopupMenu中添加菜单项JMenuItem。