Is it possible to create a Custom Widget that behaves like the 'Deprecation Errors' warning on the Dashboard? When active, the widget would appear on all users', or particular user groups, dashboards at the top and display new information, warnings and anything else that may be of use.
There’s no such thing as a “global” widget right row, however your widget’s
getBodyHtml() method can return
false, which tells Craft to not show the widget at all. So you could just have the widget assigned to all the user accounts you want, and always return
false unless there’s actually something to display.