The property sets the values of change of theme brightness. Using the
DeltaHue and the DeltaBrightness properties it is possible to receive many of various themes from one source. The values can be from-50 up to +50. The changing of the property results in the immediate changes of the theme and repainting of all its components. If at loading of the theme its values are not equal to the default values, the changes are made with the loaded theme.
