You can't. The command should be smart enough to change to white on a dark background. You can see what it should do by holding the ALT key and using the right mouse button to drag a zoom window. I would report this to your VAR or directly to GTAC is you are able.
In ST8 the helper graphics for zoom area (and pan) now use either black or white lines depending on the intensity of the background color user preference. Note that the color selection is based on the (global) background color user preference and is unable to adjust for gradient backgrounds that may differ significantly from that color (e.g., light gradient colors vs. black background user preference).
So to answer your question, yes, this has been resolved in ST8.