This function sets the layout of the dock item.
| this |
The dock item which will get it's orientation set. |
| orientation |
The orientation to set the item to. If the orientation is set to VERTICAL, the grip widget will be shown along the top of the edge of item (if it is not hidden). If the orientation is set to HORIZONTAL , the grip widget will be shown down the left edge of the item (even if the widget text direction is set to RTL). |