Access PopupMenu in Container

Hi folk´s
I am working on an WebApp.
With a Thread i load the data from an MySQL DB.
On my MainPage i have places a WebContainer with a ToolBar in it.
In the ToolBar there is an WebContainer linked to a WebContainer with a PopupMenu .

My question is how can i access the PopupMenu from my Thread to fill with data ?
Best regards

Take a look in the examples: Examples: Desktop: UpdatingUIFromThread. I recommend doing UIThreadingWithTask but either one will work for you.