An application sends a CB_LIMITTEXT message to limit the length of the text the user may type into the edit control of a combo box.
CB_LIMITTEXT
wParam = (WPARAM) cchLimit; // maximum number of characters
lParam = 0; // not used; must be zero
Parameters
cchLimit
Value of wParam. Specifies the maximum number of characters the user can enter. If this parameter is zero, the text length is set to 0x7FFFFFFE characters.
Return Values
The return value is always TRUE.
Remarks
If the combo box does not have the CBS_AUTOHSCROLL style, setting the text limit to be larger than the size of the edit control has no effect.
The CB_LIMITTEXT message limits only the text the user can enter. It has no effect on any text already in the edit control when the message is sent, nor does it affect the length of the text copied to the edit control when a string in the list box is selected.
The default limit to the text a user can enter in the edit control is 30,000 characters.