wm-ncmbuttondblclk.md

title	description	ms.assetid	keywords	topic_type	api_name	api_location	api_type	ms.topic	ms.date
WM_NCMBUTTONDBLCLK message (Winuser.h)	Posted when the user double-clicks the middle mouse button while the cursor is within the nonclient area of a window. This message is posted to the window that contains the cursor. If a window has captured the mouse, this message is not posted.	7c0f8d6e-eb37-4873-a3f8-777e8b0b22bc	WM_NCMBUTTONDBLCLK message Keyboard and Mouse Input	apiref	WM_NCMBUTTONDBLCLK	Winuser.h	HeaderDef	reference	05/31/2018

WM_NCMBUTTONDBLCLK message

Posted when the user double-clicks the middle mouse button while the cursor is within the nonclient area of a window. This message is posted to the window that contains the cursor. If a window has captured the mouse, this message is not posted.

A window receives this message through its WindowProc function.

#define WM_NCMBUTTONDBLCLK              0x00A9

Parameters

wParam

The hit-test value returned by the DefWindowProc function as a result of processing the WM_NCHITTEST message. For a list of hit-test values, see WM_NCHITTEST.

lParam

A POINTS structure that contains the x- and y-coordinates of the cursor. The coordinates are relative to the upper-left corner of the screen.

Return value

If an application processes this message, it should return zero.

Remarks

A window need not have the CS_DBLCLKS style to receive WM_NCMBUTTONDBLCLK messages.

The system generates a WM_NCMBUTTONDBLCLK message when the user presses, releases, and again presses the middle mouse button within the system's double-click time limit. Double-clicking the middle mouse button actually generates four messages: WM_NCMBUTTONDOWN, WM_NCMBUTTONUP, WM_NCMBUTTONDBLCLK, and WM_NCMBUTTONUP again.

You can also use the GET_X_LPARAM and GET_Y_LPARAM macros to extract the values of the x- and y- coordinates from lParam.

xPos = GET_X_LPARAM(lParam); 
yPos = GET_Y_LPARAM(lParam); 

Important

Do not use the LOWORD or HIWORD macros to extract the x- and y- coordinates of the cursor position because these macros return incorrect results on systems with multiple monitors. Systems with multiple monitors can have negative x- and y- coordinates, and LOWORD and HIWORD treat the coordinates as unsigned quantities.

If it is appropriate to do so, the system sends the WM_SYSCOMMAND message to the window.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Header	Winuser.h (include Windowsx.h)

See also

Reference

DefWindowProc

GET_X_LPARAM

GET_Y_LPARAM

WM_NCHITTEST

WM_NCMBUTTONDOWN

WM_NCMBUTTONUP

WM_SYSCOMMAND

Conceptual

Mouse Input

Other Resources

MAKEPOINTS

POINTS