I have uploaded a number of fixes, some have been merged into the main branch, others should be shortly. Item 1 is fixed.....
1) If i insert an event that start today and will end sunday in the calendar is only showed in the today cell,
2) If i use the button that is dispplayed at the bottom of calendar to add an event, even if the start date is correctly inserted into db it is displayed in the previous day cell while
If i insert an event using the list form it is showed in the right day in the calendar
3)Data-> legend and Month view option -> grayscaled weekend seems to do nothing
4)OPtion -> show full details always opend details view even if it is setted to NO
5) don't know if it was a feature that you want to add to this plugin but drag and drop or resising the event does not work.
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Item 2 I suspect it has to do with how the time is stored. Is it stored at UTC or local time?