A slider for the Xfce panel that can be used to adjust and/or monitor any
numeric variable. You set whatever "variable" this is by setting an adjust
command which will run when the slider is clicked or scrolled. An option is
provided to pass the value of the slider (the fraction times an adjustable
normalization factor) to the command. You get the value of the "variable" by
setting a sychronize command. The command should return a numeric value and this
value will be regarded as a fraction of a second adjustable normalization
factor.