1. The GcMultiRow.RowErrorTextNeeded event occurs only when the GcMultiRow.DataSource property of the GcMultiRow control is set or its GcMultiRow.VirtualMode property is true. Handling the GcMultiRow.RowErrorTextNeeded event is useful when the user wants to determine the error for a row depending on its state and the value it contains.
2. When the user handles the GcMultiRow.RowErrorTextNeeded event and specifies error text in the handler, an error glyph appears in the row header cells unless the GcMultiRow.ShowRowErrors or RowHeaderCell.ShowRowError property is set to false. When the user moves the mouse pointer over the error glyph, the error text appears in a ToolTip.
3. The GcMultiRow.RowErrorTextNeeded event also occurs when the value of the Row.ErrorText property is retrieved.
4. The user can use the RowIndex property to determine the state of a row or the values it contains, and use this information to change or modify the ErrorText property. This property is initialized with the row ErrorText property value, which the event value overrides.

System.Object
   System.EventArgs
      GrapeCity.Win.MultiRow.RowErrorTextNeededEventArgs

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

RowErrorTextNeededEventArgs Members
GrapeCity.Win.MultiRow Namespace
RowErrorTextNeeded Event
CellErrorTextNeeded Event