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CommonDialog.HookProc Method

Defines the common dialog box hook procedure that is overridden to add specific functionality to a common dialog box.

Namespace:  Microsoft.Win32
Assembly:  PresentationFramework (in PresentationFramework.dll)

protected virtual IntPtr HookProc(
	IntPtr hwnd,
	int msg,
	IntPtr wParam,
	IntPtr lParam


Type: System.IntPtr
Window handle for the Win32 dialog.
Type: System.Int32
Windows message to be processed by the Win32 dialog.
Type: System.IntPtr
Parameters for dialog actions.
Type: System.IntPtr
Parameters for dialog actions.

Return Value

Type: System.IntPtr
Always returns Zero.

HookProc handles dialog initialization by centering the dialog window, relative to the screen, and to set focus to the default control.

.NET Framework

Supported in: 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.