updated to-do.
Fixed tabs so they update if multiple files are loaded.
Max number of tabs is 4.
Fixed how check-boxes display -- used a grid format.
Fixed combo boxes displaying multiple entries when filling.
X-axis labeled in real-time plot.
Fixed axes labeling.
Fixed error with matplotlib -- MPL flag issue.
Fixed legend - updates and deletes old one when re-run program.
Symbols filled -- using symbolBrush command.