Change the dock orientation
In a DockPanel object, click a child object to select it.
Under Layout in the Properties panel, select a Dock value from the list (Left, Top, Right, or Bottom).
If you drag a child object of a DockPanel object on the artboard, notice that a large four-way pointer shows the directions that you can dock the object. You can use this four-way pointer as an alternative way to change dock orientation. Simply drag the object over the direction arrow that you want. Notice that the direction arrow that you select becomes highlighted, to indicate that you can drop the object to dock it in that direction.