scrollbar thumb not always appearing

[Nicolas Cueto]

Hello,

On one particular Windows pc, the thumb of a scrollbar
will not appear unless I widen the scrollbar.

However, on several other PC and Window OSs, the very
same Rev2.6 stack with the very same scrollbar  *does*
display its thumb no matter the width of the scrollbar.

Because this stack will be deployed over a variety of
WinPCs and Win OSs, I'm now worried that there may
be other PCs out there that share this problem.

Please advise.

Thank you.

--
Nicolas Cueto