ObjectDock tabs text color is determined by the background.ini, not WindowBlinds. But, the problem stated is with icon text on mouse over, not text on tabs.
I've seen this problem. It depends on where the tabbed dock is located. When I place tabbed docks in certain areas, only the bottom half (sometimes even less) of the text is visible. The top half is under the dock. I've always figured it was another of the dual monitor quirks....
I know of no fix, other than to move the dock.