Slider Width In Floatslidergrp

This is similar to the question in http://www.highend3d.com/boards/index.php?showtopic=167652 but not quite the same...

I have a floatSliderGrp and want to set the slider to be a certain length, so that one step corresponds to a particular increment (namely 1/32). The slider is to display values from 1/32 to 10. Here's my code:

CODE
    int $denominator = 32;
    float $step = 1.0 / $denominator;
    float $min_value = $step;
    flot $max_value = 10.0;

    int $label_width = 50;
    int $slider_length = $max_value * $denominator + 1;   //this might not be quite right, but that's beside the point... see below

    $my_slider =
        floatSliderGrp -l "My Slider" -field true -value 1.0 -step $scale\_step -min $min\_value -max $max\_value -columnAlign 1 right -columnWidth2 $label\_width $slider\_length -cc $scale\_slider\_command -dc $scale\_slider\_command -enable false;

The slider looks all right, except it isn't the length that I asked for. Using a different value for $slider_length has no effect on the length of the slider.

Is it that the second parameter of -columnWidth2 only specifies how much space should be give to the slider, not how long it is? If so, how do I specify how long the slider should be?

As it is, the slider is too short, and moving it by one step increases it by more than my required increment of 1/32.