tltk backend printing

[Michael D Godfrey]

Using the current hg source I noticed 2 items about printing:

1. Rendering and print() are not synchronized.  If you type print()
    before rendering of the screen plot is complete, it fails.  I am
    not sure if this happened with gnuplot, but it is more obvious
    now.  It would make sense to put a refresh in the print command
    so that it is not necessary to precede each print() with a refresh.
    This obviously usually happens in functions or scripts.  In addition,
    something odd seems to happen if you plot a number of plots in a
    script following each plot with a refresh() and print().  At about plot 4
    or 5 the refresh stops working in the sense that the plot window
    stays blank (typically black), but the print() produces the correct plot.

2. When printing a fairly large number of plots using just
    print("file.ps") --no color or other options -- occasionally the plot is in color.
    So far, it has always been that the plotted curve is in blue.
    Most of  the plots are B&W as documented.  This must be some uninitialized
    variable.

I will see what I can do about both of these, unless some one knows
exactly how to fix them.

Michael