Hi,
I try on the demo :
https://www.bryntum.com/examples/calendar/bigdataset/
I have add this :
const calendar = new Calendar({
...
weekStartDay: 1,
modes : {
agenda: {
range: 'week',
weekStartDay: 1,
}
}
...
}
It's ok on week view but on agenda view, week start with Sunday instead of Monday.