toggle preference pane visibility on button press
set output panes to be read only. Also limit size of error pane
clear error pane before running code
remove unnecessary debug messages
Dock doc/help widget at top of app and toggle with button:

* still needs content!
* need to consider navigation across docs
add more with_* methods to autocompletion
prioritise threads that are struggling to keep up...
Add more sophisticated thread priority allocation:

* Increase priority of main job thread (and therefore all subthreads)
  higher than default. 
* Permanently increase priority of threads struggling to keep up with 
  time
* Reduce priority of all background threads lower than default