Note 1 in the accept source dialog now gets focus when the dialog is 
created.  Also, the note 1 and note 2 comboboxes are no longer read only ;
any value can be entered in them.  Therefore the offered choices are 
mostly for reference when the user is still learning.
Added custom combo box class which is read-only but allows keyboard
completion of the possible choices by pressing the first character of the
choice.
This addresses the issue in #14 by keeping the possible values restricted
while still facilitating the keyboard workflow.
Merge pull request #23 from drusk/issue14

Issue14 - Note 1 focus