Gets the alpha level of the color defined by the backgroundColor property, of the image or SWF file defined by the backgroundImage style. Valid values range from 0.0 to 1.0.
For most controls, the default value is 1.0, but for ToolTip controls, the default value is 0.95 and for Alert controls, the default value is 0.9. The default value is 1.0.
protected Double backgroundAlpha { get; }
'Declaration
Protected Read Property backgroundAlpha As Double