Occurs when a cell's ToolTip text is needed.
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
When you handle the event, the ToolTip text you specify in the handler is shown whenever the mouse pointer is over a cell and the control ShowCellToolTips property value is true. The event is useful when you want to display ToolTips determined by the current state or value of a cell.
The event also occurs whenever the value of the DataGridViewCell.ToolTipText property is retrieved, either programmatically or when the mouse pointer enters a cell.
You can use the DataGridViewCellEventArgs.ColumnIndex and RowIndex properties to determine the state or value of a cell, and use this information to change or modify the DataGridViewCellToolTipTextNeededEventArgs.ToolTipText property. This property is initialized with the value of the cell ToolTipText property, which the event value overrides.
Handle the event when working with large amounts of data to avoid the performance penalties of setting the cell ToolTipText value for multiple cells. For more information, see Best Practices for Scaling the Windows Forms DataGridView Control.
For more information about handling events, see Consuming Events.