We create tree inside borderlayout as follows.
ZK --> BorderLayout --> LayoutRegion --> Div --> Panel --> PanelChildren --> VLayout --> TreeItem
When right clikcing on the tree item, the context menu gets open and when i try to resize the region with context menu open, the tree gets disappeared. When i try to resize with context menu open, it sets the height of the v-layout-inner to zero(0). Hence it disappears. Sometimes, tree disappears when we right click on the tree item to see the context menu.
Please find the sample zk file attached with this mail.