gxplor.icn: Program to explore graphics facilities

Usage:  gxplor [-s] [window options]

   gxplor is an interactive explorer for experimenting with Icon's
graphics facilities.  Commands read from standard input set window
attributes or invoke procedures.  Result values are reported on
standard output.  Errors are caught when possible.

   Here's an example, with commentary at the side,  that illustrates
some of the possibilities:

    % gxplor                        start program; a window appears
    > fg                            query value of "fg" attribute
    black
    > fg blue                       set "fg" attribute
    blue
    > linewidth 7                   set "linewidth" attribute
    7
    > drawline 12 20 55 73          a fat blue line appears
    > erasearea                     clear window
    > fillarea
    [unrecognized]                  oops -- wrong name
    > fillrectangle
    > pattern                       query "pattern" attribute
    [failed]
    > pattern grid                  set it
    grid
    > fillstyle
    solid
    > fillstyle opaque
    error 205: invalid value
    > fillstyle textured            set fillstyle
    textured
    > clip 50 50 400 200            set clipping
    > fillrectangle                 fill clipped area with pattern
    > zoom 40 40 100 100 300 50 200 200
                                    zoom a region
    > &storage                      query memory usage
    0
    274
    12184
    > exit                          exit the program
    %

   Input consists of blank-separated words, as shown.  If the first
word is recognized as the name of an attribute, a WAttrib() call is
made.  If it is an Icon keyword, the keyword value is printed.
Otherwise, the word is treated as a procedure name.  Any built-in
function or linked procedure can be invoked, and procedure names are
treated as case-insensitive for ease of entry.

   If a line begins with an integer, the remainder of the line is
interpreted as a command to be repeated that number of times.
Afterwards, the elapsed CPU and wall-clock time is reported;
these figures include loop and call overhead.

   The -s option selects "script" mode:  input is echoed on standard
output, and at EOF the program pauses in WDone().