In 8u20 for TreeView, in LTR orientation, RIGHT key expands the TreeView, and LEFT collapses the TreeView. In RTL orientation, the keys reversed.

But for TreeTableView, RIGHT key expands the TreeTableView, and LEFT collapses the TreeTableView in both LTR and RTL orientation.

Run attached test case and select "RTL Orientation", then select the root of the tree. When pressing LEFT, the TreeTable is collapsed, and then pressing RIGHT, the TreeTable is expanded. This is inconsistent with TreeView.