The Calendar squares are not text boxes nor input zones of type, so it is impossible to use them in a way which they are not designed to function. If they were input zones as you suggest, then it would impossible to set up as an event or task, set categories, set reminders, set repeats etc etc etc, which means nothing would integrate with anything. You might as well write it on a piece of paper and stick it on the fridge or use a manual calendar. The Thunderbird Calendar is a fully integrated part of the program which hooks up various aspects and functionalities using the calendar date time squares for display purposes only. They are display zones for created Event or Task headers or emails which have been converted or display of invites to events. So they are multi-purpose display zones for a variety of uses and variety of calendars. Each time/date box is also for more than one calendar. EG: I have two calendars, Home and Gmail plus a gmail My Tasks calendar utilising the same calendar square display zone for all the Events, Tasks etc. So you see, there is an overwhelmingly good reason why it is not a simple text box. People use computers to work smart otherwise there is no benefit. The Thunderbird Calendar works 'smart' pulling data from various sources into one time date zone. There is no point in storing data if you cannot use it to provide information in a useful and meaningful manner. Ways to open an event - choose the one that you prefer. As you can see access to creating an event has to be accessible via many ways to cope with those who use 'Menu Bar' toolbar and also those who cannot use a mouse. Using 'Menu Bar': click on 'Event and Tasks' and select 'New Event' Using Menu Bar' - the above method is accessible via keyboard using 'Alt'+'N' and then 'N' The above two methods mean you can open and create an event without opening the calendar or use them whilst calendar is open. Using 'Calendar Toolbar': Single click using mouse on the 'Event' button Right click in calendar square time/date zone and select 'New Event' Using a mouse: A double click in a calendar square auto opens a new Event window. Using keyboard: use 'Ctrl'+'I' as shortcut keys to open a new Event window