Today I discovered an awesome feature in Vim I would so much like to have in LibreOffice, and I bet any other person who uses greek letters sometimes, e.g. in scientific papers.

In vim, there are more than 2000 characters that you can enter by logical or at least easy to remember 2 character combinations, after activating the digraph insert mode. That is, you press a keyboard shortcut (Control+K in vim) and then the next 2 characters you enter will be interpreted as a digraph, or a 2-character combination. If the digraph exists, the characters you entered will be converted to the special character matched, otherwise the characters are deleted.

For example, pressing Control+K (to enter digraph mode) and then a: will insert in the text body the ä character (latin small letter a with diaeresis). As another example, the digraph for any greek letter is the latin version of the letter and an asterisk, e.g. a* yields α (greek small letter alpha).

A visual hint can be displayed to let the user know he is entering a digraph, like changing the character's color temporarily, or perhaps a dialog could appear with a textbox and ambitiously a dropdown menu to autocomplete digraphs.