Handle leak problem with DevComponents.DotNetBar.ItemPanel

I am using dotnetbar, version is 11.8.0.2.I encountered a problem with ItemPanel in my WinForm app. I added a few button in ItemPanel,after the form loading, I use the mouse over one button in ItemPanel ,then In the task manager of operating system I found this problem: the handles of my process increased to more than 2000, and reduced to a number (my program about 500), and then began to increase repeat the above process.it seems that the ItemPanel

control appears leakage handle resources. how to avoid this problem, thank you.