Function            shadow - draw a shadowed box

  Syntax              void shadow(int left, int top, int right,
                                  int bottom, char frame[]);

  Prototype in        video.h

  Remarks             draws a shadowed box at the coordinates (left,top)
                      to (right,bottom). The coordinates will contain the
                      box and any shadowing necessary. In the example
                      below, the smallest value for bottom should be 3,
                      which would draw:

                           abbbbbbc
                           gffffffe+
                            ++++++++


                      The characters in frame[] are used to generate the
                      frame. Also, frame must be have at least 9 elements
                      (char frame[9]). The box characters are frame[0]
                      (top left) to frame[7] (left wall), going
                      clockwise. If frame[8] != '\0' the box is filled
                      with it.

                      Video output is via Borland's console i/o. All
                      coordinates are based on the actual screen (1,1 to
                      width,height) and not the current window() setting.

                      All shadowing uses _shadowchar and _shadowcolor to
                      determine the character and color used.

                      This function does virtually no error checking.

  Return value        nothing.

  See also            video.h
                      _shadowstyle, _shadowchar, _shadowcolor
                      box(), boxwindow()

  Example             #include <video.h>

                      main()
                      {
                           extern int _shadowstyle;
                           extern char _shadowchar;
                           char framebox[] = "abcdefgh";

                           _shadowstyle = SHADOW_R|SHADOW_BR|SHADOW_B;
                           _shadowchar = '+';
                           shadow(1,1,9,5,framebox);
                      }

  Program output      abbbbbbc
                      h      d+
                      h      d+
                      gffffffe+
                       ++++++++