Custom Draw
The SpreadsheetControl allows you to custom draw worksheet cells via the SpreadsheetControl.CustomDrawCell and SpreadsheetControl.CustomDrawCellBackground events. Use the CustomDrawObjectEventsArgs.Graphics property to return an object providing a basic means for painting. Use the methods and properties of this object to paint text, graphic primitives or images. Custom drawing allows you to customize the appearance of a document. Note, however, that custom draw modifications are not saved in the workbook file. You can use the custom draw functionality to display additional information to end-users, or highlight cell content.
The image below demonstrates how the custom draw feature can be used to display a callout above a cell containing an incorrect formula result.
