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SetWindowLongW.3w

NAME

SetWindowLongW (USER32.@)

SYNOPSIS

LONG SetWindowLongW
 (
  HWND hwnd,
  INT  offset,
  LONG newval
 )

PARAMS

hwnd [In] window to alter.

offset [In] offset,in bytes,of location to alter.

[In] new value of location.

DESCRIPTION

SetWindowLongW (USER32.@) Set window attribute.

SetWindowLong() alters one of a window's attributes or sets a 32-bit (long) value in a window's extra memory.

The _hwnd_ parameter specifies the window. is the handle to a window that has extra memory. The _newval_ parameter contains the new attribute or extra memory value. If positive, the _offset_ parameter is the byte-addressed location in the window's extra memory to set. If negative, _offset_ specifies the window attribute to set, and should be one of the following values:

GWL_EXSTYLE The window's extended window style.

GWL_STYLE The window's window style.

GWLP_WNDPROC Pointer to the window's window procedure.

GWLP_HINSTANCE The window's pplication instance handle.

GWLP_ID The window's identifier.

GWLP_USERDATA The window's user-specified data.

If the window is a dialog box, the _offset_ parameter can be one of the following values:

DWLP_DLGPROC The address of the window's dialog box procedure.

DWLP_MSGRESULT The return value of a message that the dialog box procedure processed.

DWLP_USER Application specific information.

RETURNS

If successful, returns the previous value located at _offset_. Otherwise, returns 0.

NOTES

Extra memory for a window class is specified by a nonzero cbWndExtra parameter of the WNDCLASS structure passed to RegisterClass(3w) at the time of class creation.

Using GWL_WNDPROC to set a new window procedure effectively creates a window subclass. Use CallWindowProc(3w) in the new Windows(tm) procedure to pass messages to the superclass's window procedure.

The user data is reserved for use by the application which created the window.

Do not use GWL_STYLE to change the window's WS_DISABLED style; instead, call the EnableWindow(3w) function to change the window's disabled state.

Do not use GWL_HWNDPARENT to reset the window's parent, use SetParent() instead.

Win95: When offset is GWL_STYLE and the calling app's ver is 4.0, it sends WM_STYLECHANGING before changing the settings and WM_STYLECHANGED afterwards. App ver 4.0 can't use SetWindowLong to change WS_EX_TOPMOST.

IMPLEMENTATION

Defined in "winuser.h".

Implemented in "dlls/user32/win.c".

Debug channel "win".