Mark emails unread in Lotus Notes

One of the things that annoyed me about Lotus Notes was the inability to easily mark emails as unread once opened. However today I accidentally found out that by pressing the Insert key this will toggle the read/unread state of the email. However, if you have a mixed state of read and unread mails, then all the mails turn to one state which will be the opposite state of the currently selected email.
I asked around in the office and nobody knew this trick - I discovered it by accident when trying to delete an email and I missed the key. The only downside to the trick is if you miss the insert button and hit delete instead - I am not responsible for any sudden outbursts of swearing if this happens!