[plt-scheme] request simple scheme code

Today I had an epiphany about something I have wanted to do for
several years.  I know tcl/tk can do what I want, but they are slower
than I want and I want to use scheme.  Will someone help me please
with some starter code?

What I want is for the plt-scheme program to call an external program
that will generate some data.  I want this data plotted on a canvas
(is that the right word?) as a line plot that if the plot is larger
than the display window there are scroll bars (horizontal and
vertical) to allow displaying of the plotted data.

The application is a simple stock program to display a few custom
values I am calculating in the external program. The sample scheme
code would be great if it had some number (10?) of values in a list
(or should it be an array?) and that list is handed to the plotting
routine for display.

The eventual application I have in mind a window that has a series of
stock symbols vertically down the left side.  If the list is larger
than the display window, the list scrolls.  These stock symbols are
buttons and when clicked, the external program is called to retrieve
the data, then the data is plotted on an adjacent window to the right
for scrolling as necessary.

Does that make sense?

+------+---------------------+
| SYM1 |           .     .   |
|-SYM2-|          . .   .    |
| SYM3 |         .   . .     |
| SYM4 |    .   .     .      |
| SYM4 |   . . .             |
| SYM5 |  .   .              |
| SYM7 | .                   |
+------+---------------------+

I realize this question(s) relates to more than constructing
(define)'s and I appreciate any help given. I am looking to jump-start
my efforts writing the above program. Seems like I need to download
DrScheme to my iMac (aqua) for writing this. The C and perl, etc,
is easy and mostly done.

Mike