Sometimes I click on the 'follow up' flag icon for an email in the inbox, and nothing happens. Or there's a message to say the flag was set but it doesn't change colour and doesn't appear in the to do list.
Workaround: Click on the follow up flag for a different email, then clear it, then click back on the first one.
A piggy bank of commands, fixes, succinct reviews, some mini articles and technical opinions from a (mostly) Perl developer.