TextBoxBase.GetCharIndexFromPosition Method (Point)
Retrieves the index of the character nearest to the specified location.
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
This method returns the character index that is closest to the position specified in the pt parameter. The character index is a zero-based index of text in the control, including spaces. You can use this method to determine where in the text the user has the mouse over by passing the mouse coordinates to this method. This can be useful if you want to perform tasks when the user rests the mouse pointer over a word in the text of the control.
If the specified location is not within the client rectangle of the control, or is beyond the last character in the control, the return value is the index of the last character.
Available since 2.0