Moveable cursor working. Draws incorrectly

The cursor draws in each position it has been in starting from the
right of the inputString.  I'm trying to track down the problem.
Also, occasionally the cursor doesn't show at all even though the
string can be editted as normal.  Not sure what exactly is causing
this but I'm looking around.
Further textbox features implemented

Insertion at cursor, cursor movement, bounded inputString, invalid
index protection, and small graphical enahncements added.  All that
remains for the textbox for the time being is preventing overflow
over the end of the box. Then it's all done.(for snake, at least)
Removed debugging print statements
Added means of preventing buffer overflow

A method to check if cursor is at the end of the buffer has been
added and ensures the input stops at the end of the buffer.