mozilla-release/layout/reftests/native-theme/scroll-thumb-minimum-size-notheme.html

<!DOCTYPE html>
<div style="width: 200px; height: 200px; overflow: scroll;; -moz-appearance:none">
  <div style="width: 3725px; height: 3725px"></div>
</div>
<!--
The size of the inner div is computed as follow:

Input:
  outer_div_size: size of the div containing the scrollbar
  button_size: size of the scrollbar arrow buttons
  scrollbar_thickness: width/height of a vertical/horizontal scrollbar respectively
  thumb_size: height/width of the thumb of a vertical/horizontal scrollbar respectively
Output:
  inner_div_size: size of the div to be scrolled

Formula:
  slider_size = outer_div_size - 2 * button_size - scrollbar_thickness
  thumb_size = slider_size * (outer_div_size / inner_div_size)
 which gives:
  inner_div_size = (outer_div_size - 2 * button_size - scrollbar_thickness) * (outer_div_size / thumb_size)

Testcase constants:
  outer_div_size = 200

On XP/Vista at 96 dpi with theme disabled:
  thumb_size = 8 (minimum size)
  button_size = 17
  scrollbar_thickness = 17

  inner_div_size = (200 - 2 * 17 - 17) * (200 / 8) = 3725
-->