org.zkoss.zul.tree.rightSelect
From Documentation
Property:
org.zkoss.zul.tree.rightSelect
Default: true [Since 5.0.5]
If a tree's checkmark (Tree.isCheckmark()) is enabled, the selection will be toggled when the user right clicks item.
If you prefer not to select/deselect item on right click, you could specify false to this library property.