By clicking the "todo list" button, You get a moveable popup box.
The "box" can be moved by left-mouse-down-hold, and then place it where You like.
When hovering over the upper-right X it becomes red. If You click on it, the window closes again.
In top is shown a date interval.
This date interval is depending on the settings, in combination with the date in the date-picker field.
When clicking on an event in the list, a special eventwindow opens, and You can checkout the todo-field and save the event, or close the window without making any changes.
In the calendar view, the event is now shoving the todo-mark in the todo-field.