An inexplicable change of behaviour

[kinook]

docType of 6 is RTF, 7 is Text.

For Text documents, if Tools | Options | Editor | Use syntax coloring editor for text files is checked, the syntax coloring editor will be used (which has a margin with line numbers), and the font is configured via right-click | Options -> Editor Font in the editor. If unchecked, the rich text editor will be used, with the Tools | Options | Editor | Text document editor font.

For RTF documents, the rich text editor will be used, with the Tools | Options | Editor | Default rich text editor font.

These options apply to all databases.

Ultra Recall does not normally change a document from Text to RTF or vice versa.