See attached sample: start it, click the button, and a new Aspose.Cells workbook is created and shown in GridDesktop in readonly mode. 
GridDesktopTest.zip (5.2 KB) 
Problem 1: 
Switch to “Sheet 1”, then use the mouse wh…...get_Item(Int32 index) at Aspose.Cells.GridDesktop.WorksheetCollection...WorksheetCollection. (Int32 ) at Aspose.Cells.GridDesktop.WorksheetCollection...