If there are AutoSizeRows = true and TextBox column with Multiline=true then puting the column in edit mode is impossible. 

Please note that this worked with Q2 2009 SP1, but there are two glitches:
- in the first edit, the grid's row loses its heigh
- In edit mode if arrow up key is used to navigate inside the text when cursor is in second row, next arrow up press brings the cursor to upper cell instead to the first row of the text.

When MessageBox is used in CellValidating event and during editing the RadGridView loses focus (for example click on button outside the grid), the event has been thrown twise.

The last text line is cut off

If RadGridView is instanced, but not added to form's controls or its Visible property is set to false, the ExportToExcelML fails with exporting blank file or throwing exception.

The exception occurs only when AutoSizeRows is set to true and the binding code is inside the form's constructor.

In a DateTime column if you creating a new row, when enter into a DateTime cell the default date appears, but when you procceed to the next cell it does not saved. You have to open the DropDown Calendar and chose the same date as already shown to save it in the newly created row.

When adding new row, before finishing it - leave the grid focus (click a button outside the grid for example). The new row has been added but RowValidating event does not thrown.

Add similar like DateColumn.DateTimeMode property for GridViewDateTimeColumn. Link in MSDN: http://msdn.microsoft.com/en-us/library/system.data.datacolumn.datetimemode.aspx

When you have a parent-child relation in GridView and try to add a new row in the datasource programmatically, the new row does not appear in the child table. Note: At the first time the row is shown. If you try to add second new row, it does not appear in the grid.