Gadget: NumberRange
Bits: 0 - Set means inform client of changes using NumberRange_ValueChanged
2 - Set means writable field (unset is display).
3 - Set means no display area.
4 - Set means has adjuster arrows.
5-7 - Slider type:
0 - No slier.
1 - Slider to right of display.
2 - Slider to left of display.
8-9 - Justification:
0 - Left.
1 - Right.
2 - Centred.
12-15 - Desktop colour of slider bar.
16-19 - Desktop colour of slider background.
