I am attaching a demo project showing how to implement custom ui layer in RadSpreadsheet. This way subscribing for changes in the selection, a tooltip is shown on the active cell index if it is in some desired range. A TooltipManager class is responsible for validating on which cell a tooltip will be shown (in the example the cells with green background has tooltip).
As for the StatusBar, currently Spreadsheet's status bar is not easily customizable. That is why the best I can suggest is to implement your own statusbar, where you can log messages when needed.
Additionally I would like to point out that the UpdateUIOverride method in TooltipUILayer has two implemented overloads. That is because the overload using WorksheetUIUpdateContext is obsoleted and will soon be removed from RadSpreadsheet's API. That is why it is a good idea to use both overloads and next Q when the obsoleted method is removed you will have to simply delete its implementation from the attached sample project in order to build it successfully.
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