Steps to Reproduce

run the attached example and click the button "select item 3.2"

Actual Result

the group box opens and
the tree is shown at the top scroll position

Expected Result

the group box opens and
the selected tree item is visible (scrolled into view)

Debug Info

this works after the group box has been opened once
subsequent button clicks will open the groupbox and scroll to the correct position

happens unrelated to model based or static tree composition (tree-scroll-on-open-simple.zul tree-scroll-on-open-model.zul)