The MaskedTextBox.InsertKeyMode property controls the character insertion behavior of the System.Windows.Forms.MaskedTextBox control. The state of this property is defined by the System.Windows.Forms.InsertKeyMode enumeration, which can be always on, always off or set to respect the setting of the user's keyboard. This property supersedes the insertion mode of the keyboard. For example, if the keyboard is set to overwrite, but MaskedTextBox.InsertKeyMode is set to Insert, the System.Windows.Forms.MaskedTextBox will operate in insert mode. The MaskedTextBox.IsOverwriteMode property will access the true insertion mode of the System.Windows.Forms.MaskedTextBox.

If changing MaskedTextBox.InsertKeyMode changes the value of MaskedTextBox.IsOverwriteMode, System.Windows.Forms.MaskedTextBox will raise the MaskedTextBox.IsOverwriteModeChanged event.

This property has no effect if no mask has been set.