class TGTripleHSlider: public TGDoubleHSlider

TGTripleVSlider and TGTripleHSlider

TripleSlider inherit from DoubleSlider widgets and allow easy
selection of a min, max and pointer value out of a range.
The pointer position can be constrained to edges of slider and / or
can be relative to the slider position.

To change the min value press the mouse near to the left / bottom
edge of the slider.
To change the max value press the mouse near to the right / top
edge of the slider.
To change both values simultaneously press the mouse near to the
center of the slider.
To change pointer value press the mouse on the pointer and drag it
to the desired position

Dragging the slider will generate the event:
kC_VSLIDER, kSL_POS, slider id, 0  (for vertical slider)
kC_HSLIDER, kSL_POS, slider id, 0  (for horizontal slider)

Pressing the mouse will generate the event:
kC_VSLIDER, kSL_PRESS, slider id, 0  (for vertical slider)
kC_HSLIDER, kSL_PRESS, slider id, 0  (for horizontal slider)

Releasing the mouse will generate the event:
kC_VSLIDER, kSL_RELEASE, slider id, 0  (for vertical slider)
kC_HSLIDER, kSL_RELEASE, slider id, 0  (for horizontal slider)

Moving the pointer will generate the event:
kC_VSLIDER, kSL_POINTER, slider id, 0  (for vertical slider)
kC_HSLIDER, kSL_POINTER, slider id, 0  (for horizontal slider)

Use the functions GetMinPosition(), GetMaxPosition() and
GetPosition() to retrieve the position of the slider.
Use the function GetPointerPosition() to retrieve the position of
the pointer