DTN_FORMATQUERY notification code
Sent by a date and time picker (DTP) control to retrieve the maximum allowable size of the string that will be displayed in a callback field. This notification code is sent in the form of a WM_NOTIFY message.
DTN_FORMATQUERY lpDTFormatQuery = (LPNMDATETIMEFORMATQUERY) lParam;
A pointer to an NMDATETIMEFORMATQUERY structure containing information about the callback field. The structure contains a substring that defines a callback field and receives the maximum allowable size of the string that will be displayed in the callback field.
The owner of the control must calculate the maximum possible width of the text that will be displayed in the callback field, set the szMax member of the NMDATETIMEFORMATQUERY structure, and return zero.
Handling this notification code prepares the control to adjust for the maximum size of the string that will be displayed in a particular callback field. This enables the control to properly display output at all times, reducing flicker within the control's display. (For additional information about callback fields, see Callback fields.)
|Minimum supported client
||Windows Vista [desktop apps only]
|Minimum supported server
||Windows Server 2003 [desktop apps only]
|Unicode and ANSI names
||DTN_FORMATQUERYW (Unicode) and DTN_FORMATQUERYA (ANSI)