Customise Desktop

I think the desktop is handy but I'm unsure how it is liked to the available tools. For example a few of the different tools have reminders, Planner, Calendar, Groups etc but I actually can't find which updated the desktop reminder area.

It would be great to customise the Desktop with a more synchronised grouping of all notes, Tasks, Events etc together.

Or if I add an app like Planner or Invoice the ability to add a summary to the desktop for these if I need.

Thanks