This has been an annoying problem for a long time. With a dark color theme for KDE4, Openoffice.org's Calc does not honor the background colors. Which widget's color (in Systemsettings > Appearance > Colors) should I modify to get the desired result? Note that Openoffice.org's Writer works fine. Here are some examples:
With a light theme (or even a slightly darker theme such as Wonton Soup):


With a dark theme (Obsidian Coast):
As you can see the bg in the spreadsheet is not imposed.

For sanity, I have forced Openoffice.org's appearance to have a Document background of white and Font color of black this way (all other interface elements are automatic):


Thanks.

I think the solution you found is the right one.

OpenOffice is not actually a real KDE app - it only pretends to be one, so it sometimes does some things inconsistently.

So, there is no way one can modify Obsidian Coast (or anything else in Openoffice.org) to behave properly with Openoffice.org?

The colour theme can be customised from the shipped theme values through the colour KCM I believe. ( System Settings > Appearance > Colour )