_List of Desired Features_

Categories work based on selection, not just highlight
 - i.e. assign categories to multiple books at once
 - this may involve extra logic if books don't have the same categories beforehand
Regex Search
Choose shown columns in browser
Support for multiple copies
 - (better support, that is)
 - some way of identifying the physical ones with the virtual ones


_Code Quality Improvements_
Document all functions
Conform to python naming conventions and code style
Make db_layer use a helper function to handle most of the database queries


_Bugs_
Error when entering bad ISBN e.g. 02010798X (instead of 020107981X)
 - seems to be an intermittant error, likely related to polling openLibrary
Error on search 
 - related to strings in Python3
When the top element shown is highlighted in the browser window, and pgUp is pressed (causing a scrollup), the bottom border of the window turns into 'qqqqqqqq'.
 - does not happen when up_arrow is pressed.




_Implemented Features_
Sort by column in browser
Support UTF-8 for everything
Search ignores Case (for lowercase search strings)
Text entry supports longer string
Home and End navigate to top and bottom of catalogue respectively.