The widget of interest.
The value for the horizontal alignment.
If the layout width allocated to a widget is larger than its max width, the horizontal alignment controls how the widget is placed within the extra horizontal space.
If the allocated width is less than the widget's max width, the horizontal alignment has no effect.
Some layout implementations may ignore horizontal alignment.
Changing the horizontal alignment will post an update-request
message to widget's parent, provided the parent has a layout
installed.
Set the horizontal alignment for a widget.