(Not available in the Lite version)
When you add or edit a gradient wallpaper, you will get the following window.
This window allows you to manipulate your gradient. The "Name" is a required field. The "Gradient Type" specifies the type of the gradient, which can be:
Some of the above gradient types have there origin in the lower left corner of the gradient. In that case you can use an X-Offset and Y-Offset of 50 to center the gradient.