This all happens on my x64 Linux workstation btw. tl;dr: My colleague invited some people and me for a meeting. The meeting was scheduled a week to late. I -wrongfully- accepted. How do I propose a new time? To explain a bit more in detail: I received a meeting request in my mailbox. Thunderbird is so nice to let me accept or reject it, and after I click the button to accept, it is directly added to my calendar. But when I double click on the meeting to edit it, I get a function-wise scaled-down version of the meeting: The only settings I can alter are whether I want reminders, and if I go at all. Trying to drag it to another day doesn't work either: My calendar behaves like read-only (which it isn't btw). There are several questions (without answer...) to be found on Stack Overflow and on the Thunderbird knowledge base about using lightning. But I get the idea that I'm one of the few who won't comply with the team even before the meeting is started. My googling revealed no bugs or feature requests in the direction I'm thinking. A link to an explanation how to achieve this, or another perspective about how to reach the desired goal (meeting with my colleagues and me) would be mostly welcome!