According to the doc for TBox:Draw(), one can force contours to be drawn for TBox-es with fill style set by using the draw option "l". However, this doesn't seem to work for me. The attached python script reproduces the issue.
Sorry if I misunderstood something!
PS. I was a bit confused by the documentation for this function at first, and I think it could benefit from some punctionation improvements:
If the box has no fill style (ie fill style=0), the box contour is drawn. If the box has a fill style, the box contour is not drawn by default. To force the contour to be drawn, specify option "l"