This is a simple suggestion:
At the moment, the default key for adding an event is 'M', while deleting an event is 'Delete'... but also 'M'.
You can see the problem here - it is way too easy to delete events, because the same key is used to add, as well as delete them. When editing videos, I often press M thinking I'm adding another event, but don't realize that I've deleted it until it's too late - now I have to go back in time to find when I placed the marker, which is obviously a pain.
The solution? Easy. Just remove 'M' as a function for deleting events. Instead, have 'M' as an "add event marker" button only, while keeping the 'Delete' button for deleting event markers. Makes sense, right?