Code distorting in text (re: #218)

[brideylea]

Hi Conal,

Submitting this bug on behalf of Gari. This is in reference to a previous Github issue (#218). When working on a transcription, errors are occurring in the code when highlighting text. In some instances clicking 'save' corrects the code, but other times the code is actually changing (not just superficially) and resulting in errors e.g. line 7 in the first image and line 8 in the second image.

See also images 3 and 4 for further instances.