Hi

When I move my scroll wheel on the mouse, the zoom only zooms out no matter what direction the wheel is moved in. I have to delete the plot and start over. What am I doing wrong? I'd really like to be able to manually input limits for the axis's using the key pad.

Great Program!

Use the plot options that are displayed on the right side panel. If the scale option is selected, it will zoom out your plots, if you select the refresh option, your plot will be redrawn, I know you can define the plot intervals of what you want to plot using an if statement:
Example.
For more information read the Wiki/graphs.