Syntax highlighting and indentation for Latex and HTML
Latex and HTML code should have a different color than normal text. That way it would be much more readable.
I just found out about a feature, which I wanted to suggest. ^^ Ctrl+Tab indents text in the edit window.
Indenting multiple lines of text, could be nice feature. For example: select some lines and then use Ctrl+Tab to indent all selected lines. Well, this feature, will probably not be added before mnemosyne 20.1, but maybe the devellopers will get bored one day. ;)