Defines how to fill a shape. Four types of fills can be used: solid, linear gradient, radial gradient and pattern. See dojox/gfx.LinearGradient, dojox/gfx.RadialGradient and dojox/gfx.Pattern respectively for more information about the properties supported by each type.
The type of fill. One of 'linear', 'radial', 'pattern' or undefined. If not specified, a solid fill is assumed.