[Serna] Bug - Serna 4.1b on Mac OS X

I just installed 4.1b under Mac OS X 10.5.4 on an Intel-based MacBook, and
encountered one serious problem:  I can't resize the main window by
click-dragging the lower left corner. There's no "grab handle" (although the
window can be maximized with the green button in the upper right).

Bob