How to show the right expand icon(+) on treegrid?

[adoin]

Hi there,
I have some treegrid which always show the expand icon "+".
Evan it is last level.
The folder icon has been replace by getIcon() already, but this expand still not good.

For the current solution, we find
dataProperties: { dataArrived: function (parentNode) { this.openAll(); this.closeAll(); } } can fix this. BUT! some times it cause other issue like click trigger be lower performance. Can u guys share the better solution to me? Thanks.

[Isomorphic]

See treeGrid.showOpener.

[adoin]

See treeGrid.showOpener.

Solved through set isForder Thanks.