I have recently switched from MS Outlook to Thunderbird/Lightning. So far, reasonably so good. One thing that continues to frustrate me is an issue with calendar reminder popups. I thought I was not getting them, but now I think I'm getting them but they disappear. Some research suggests that it may have already been reported that reminder popups will disappear once Thunderbird checks for new mail, and what I'd vastly prefer is for a calendar reminder popup to stay, well, popped-up until I dismiss it. Am I missing something? Maybe a setting somewhere? Or is this a known issue that has yet to be solved? I did have a massive problem when I imported my Outlook calendar in that I got reminder popups for every calendar entry back to the dawn of time, and which would NOT dismiss no matter how many times I tried, so I enabled the setting to not remind me about past events. It seems as if I may have to choose between two unacceptable options: either re-enable reminders for past events, so that when Thunderbird checks for mail any undismissed reminder popups will remain (or re-popup), or live with the reminder popups disappearing (and, the whole reason I'm writing this, I'll miss calendar events if I don't happen to be glued to my computer for the 30 minutes the popup will exist). Is there not some other option?