The user interfaces mostly use :
- the Ctrl modifier for an action,
- the Alt and Alt Gr modifier for special caracters.

For exemple, Thunderbird uses the Ctrl-Enter key combination in order to send immediatly the email while it is composed.

The default Ctrl-Enter key combination for inserting a new line in a cell leads to mistakes. For example, I spent half an hour editing a Calc document with a lot of new lines in cells. When I came back to Thunderbird in order to send this document, I sent immediatly the email I was still writing just because I typed Ctrl-Enter in order to insert a new line because I didn't update the key map I had in mind when I took an other tool. This mistake couldn't occur with M Excel because it has Alt-Enter key combination instead.