WM_MBUTTONDOWN

WM_MBUTTONDOWN

fwKeys = wParam; /* key flags */

xPos = LOWORD(lParam); /* horizontal position of cursor */

yPos = HIWORD(lParam); /* vertical position of cursor */

The WM_MBUTTONDOWN message is posted when the user presses the middle mouse button while the mouse cursor is in the client area of a window. If the mouse is not captured, the message is posted to the window beneath the cursor. Otherwise, the message is posted to the window that has captured the mouse.

Parameters

fwKeys

Value of wParam. Indicates whether various virtual keys are down. This parameter can be any combination of the following values:

Value Description

MK_CONTROL Set if CTRL key is down.
MK_LBUTTON Set if left mouse button is down.
MK_RBUTTON Set if right mouse button is down.
MK_SHIFT Set if SHIFT key is down.

xPos

Value of the low-order word of lParam. Specifies the x-coordinate of the mouse cursor. The coordinate is relative to the upper-left corner of the client area.

yPos

Value of the high-order word of lParam. Specifies the y-coordinate of the mouse cursor. The coordinate is relative to the upper-left corner of the client area.

Return Value

An application should return zero if it processes this message.

Comments

An application can use the MAKEPOINTS macro to convert the lParam parameter to a POINTS structure.

See Also

GetCapture, SetCapture, WM_MBUTTONDBLCLK, WM_MBUTTONUP