Treeitem setOpen doesn't load children

To reproduce this bug simply take the TreeModelDemo and replace the last line of the render method of PersonTreeitemRenderer:

item.setOpen(false);

with

item.setOpen(true);

the tree is loaded incorrectly, the items seems to be open (they have the "-" image) but children are not loaded.
To open them you have to close it (the icon becomes "+") and then reopen.

Bye