RtTrend background color

I have an application with two RtTrend widgets, on different windows. They
are set up identically in terms of colors etc. but are different sizes. On
seems ok, the other however seems to loose its background color when first
shown (appears transparent ?). It updates as it should and the traces are
the correct color. If I cover the widget and cause it to redraw the
background (Pg_BLACK) is there, if I partially cover it the background
scrolls along the widget with the traces. I have checked the widget in the
update loop and it thinks the background color is Pg_BLACK.
Any help on this would be appreciated.

Further to my previous posting I have now discovered that the problem seems
to be caused by the Trend being on a Pane that can be covered by the Panes

If I cover the Trend with a window then expose it the background (and
border) is there. If I then cause a brother Pane to cover it
(PtWidgetTofront…) then bring the Pane with the Trend on it to the front
in the same manner the background and border have gone transparent again,
but the traces (trend data) are correctly displayed.

Hope this helps someone to help me