At any given moment, a given slider will have a
single 'selection' that is considered to be its
value, which is constrained to be within the range of
values the slider represents (that is, between its
minimum and maximum values).
Typically, sliders will be made up of five areas:
On some platforms, the size of the slider's thumb can be
varied relative to the magnitude of the range of values it
represents (that is, relative to the difference between its
maximum and minimum values). Typically, this is used to
indicate some proportional value such as the ratio of the
visible area of a document to the total amount of space that
it would take to display it. SWT supports setting the thumb
size even if the underlying platform does not, but in this
case the appearance of the slider will not change.
Note: Only one of the styles HORIZONTAL and VERTICAL may be specified.
IMPORTANT: This class is not intended to be subclassed.