The EN_MAXTEXT notification message is sent when the current insertion has exceeded the specified number of characters for the edit control. The insertion has been truncated.
This message is also sent when an edit control does not have the ES_AUTOHSCROLL style and the number of characters to be inserted would exceed the width of the edit control.
This message is also sent when an edit control does not have the ES_AUTOVSCROLL style and the total number of lines resulting from a text insertion would exceed the height of the edit control.
The control's parent window receives this notification message through a WM_COMMAND message.
wParam
Specifies the identifier of the edit control.
lParam
Specifies the handle of the edit control in the low-order word, and specifies the EN_MAXTEXT notification message in the high-order word.