extjs: How to fill combo box with tree node's immediate children?

Question

Hi,

I have a tree and a combo box.

1. I need to get the immediate children of node 1 and place them in the combo box.

2. When a node is selected from the combo box list, the tree should display only that node and its children.

Basically, the combo box serves as a filter to show only a specific node. All the nodes except from the selected one are hidden.

Any help will be appreciated.