WM_MDICREATE message

An application sends the WM_MDICREATE message to a multiple-document interface (MDI) client window to create an MDI child window.

#define WM_MDICREATE                    0x0220

Parameters

wParam

This parameter is not used.

lParam

A pointer to an MDICREATESTRUCT structure containing information that the system uses to create the MDI child window.

Return value

Type: HWND

If the message succeeds, the return value is the handle to the new child window.

If the message fails, the return value is NULL.

Remarks

The MDI child window is created with the window style bits WS_CHILD, WS_CLIPSIBLINGS, WS_CLIPCHILDREN, WS_SYSMENU, WS_CAPTION, WS_THICKFRAME, WS_MINIMIZEBOX, and WS_MAXIMIZEBOX, plus additional style bits specified in the MDICREATESTRUCT structure. The system adds the title of the new child window to the window menu of the frame window. An application should use this message to create all child windows of the client window.

If an MDI client window receives any message that changes the activation of its child windows while the active child window is maximized, the system restores the active child window and maximizes the newly activated child window.

When an MDI child window is created, the system sends the WM_CREATE message to the window. The lParam parameter of the WM_CREATE message contains a pointer to a CREATESTRUCT structure. The lpCreateParams member of this structure contains a pointer to the MDICREATESTRUCT structure passed with the WM_MDICREATE message that created the MDI child window.

An application should not send a second WM_MDICREATE message while a WM_MDICREATE message is still being processed. For example, it should not send a WM_MDICREATE message while an MDI child window is processing its WM_MDICREATE message.

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 Windows.h)

See also

Reference

CreateMDIWindow

CREATESTRUCT

MDICREATESTRUCT

WM_CREATE

WM_MDIDESTROY

Conceptual

Multiple Document Interface