These boxes should use the same background color as the text background colors of the source windows. For example, I use a dark blue color for the background of my source windows, but since VAX uses white, I can't read any of the text in the Context and Definition fields.
Of course, if you do this, you lose the advantages of syntax colouring in those windows. I suggested in thread 1331 a second set of text colours for those light-background windows. I don't know if they're considering this.