VB.NET, C#
Xceed Grid for WinForms gives you complete control over how errors are displayed.
Row selector: blink, show icon, show tool tip
Entire row: blink, change color, show tool tip
Cell: blink, change color, show tool tip
Change blink style
How to handle the LeavingEdit and EditLeft events of the Cell objects
How to handle the EditCanceled event of a DataRowTemplate
In the Activate/Deactivate visual cues for errors section, select one of the error display types you wish to see and enter invalid data in the grid.
C#: Xceed Samples\Xceed Grid for WinForms v#.#\CSharp\ErrorDisplay\Xceed.Grid.Samples.ErrorDisplay.csproj
VB.NET: Xceed Samples\Xceed Grid for WinForms v#.#\Visual Basic .NET\ErrorDisplay\Xceed.Grid.Samples.ErrorDisplay.vbproj