richTextBox undo behavior is buggy

[RedDragonWebDesign]

1. paste good tests
2. select all, paste bad tests over it
3. add a space to a random word
4. hit ctrl-z (undo). space is not deleted.
5. hit ctrl-z a couple more times. the good tests text comes back, but appended to the end of the bad tests list

[RedDragonWebDesign]

Also, paste over old text with new text. Then Ctrl-Z. It will leave the new text, and put the old text beneath it.

[RedDragonWebDesign]

Can potentially solve this by using document.execCommand(). That plays nicely with undo and redo.

Can potentially re-factor to use document.execCommand(hiliteColor, ??, "Orange"). Might also fix the richTextBox cursor issue