CreateWindowEx info  Overview  Group

The CreateWindowEx function creates an overlapped, pop-up, or child window with an extended style; otherwise, this function is identical to the CreateWindow function. For more information about creating a window and for full descriptions of the other parameters of CreateWindowEx, see CreateWindow.

HWND CreateWindowEx(

DWORD dwExStyle,	// extended window style
LPCTSTR lpClassName,	// pointer to registered class name
LPCTSTR lpWindowName,	// pointer to window name
DWORD dwStyle,	// window style
int x,	// horizontal position of window
int y,	// vertical position of window
int nWidth,	// window width
int nHeight,	// window height
HWND hWndParent,	// handle to parent or owner window
HMENU hMenu,	// handle to menu, or child-window identifier
HINSTANCE hInstance,	// handle to application instance
LPVOID lpParam	// pointer to window-creation data
);

Parameters

dwExStyle

Specifies the extended style of the window. This parameter can be one of the following values:

Style	Meaning
WS_EX_ACCEPTFILES	Specifies that a window created with this style accepts drag-drop files.
WS_EX_APPWINDOW	Forces a top-level window onto the taskbar when the window is minimized.
WS_EX_CLIENTEDGE	Specifies that a window has a border with a sunken edge.
WS_EX_CONTEXTHELP	Includes a question mark in the title bar of the window. When the user clicks the question mark, the cursor changes to a question mark with a pointer. If the user then clicks a child window, the child receives a WM_HELP message. The child window should pass the message to the parent window procedure, which should call the WinHelp function using the HELP_WM_HELP command. The Help application displays a pop-up window that typically contains help for the child window. WS_EX_CONTEXTHELP cannot be used with the WS_MAXIMIZEBOX or WS_MINIMIZEBOX styles.
WS_EX_CONTROLPARENT	Allows the user to navigate among the child windows of the window by using the TAB key.
WS_EX_DLGMODALFRAME	Creates a window that has a double border; the window can, optionally, be created with a title bar by specifying the WS_CAPTION style in the dwStyle parameter.
WS_EX_LEFT	Window has generic “left-aligned” properties. This is the default.
WS_EX_LEFTSCROLLBAR	If the shell language is Hebrew, Arabic, or another language that supports reading order alignment, the vertical scroll bar (if present) is to the left of the client area. For other languages, the style is ignored and not treated as an error.
WS_EX_LTRREADING	The window text is displayed using Left to Right reading-order properties. This is the default.
WS_EX_MDICHILD	Creates an MDI child window.
WS_EX_NOPARENTNOTIFY	Specifies that a child window created with this style does not send the WM_PARENTNOTIFY message to its parent window when it is created or destroyed.
WS_EX_OVERLAPPEDWINDOW	Combines the WS_EX_CLIENTEDGE and WS_EX_WINDOWEDGE styles.
WS_EX_PALETTEWINDOW	Combines the WS_EX_WINDOWEDGE, WS_EX_TOOLWINDOW, and WS_EX_TOPMOST styles.
WS_EX_RIGHT	Window has generic “right-aligned” properties. This depends on the window class. This style has an effect only if the shell language is Hebrew, Arabic, or another language that supports reading order alignment; otherwise, the style is ignored and not treated as an error.
WS_EX_RIGHTSCROLLBAR	Vertical scroll bar (if present) is to the right of the client area. This is the default.
WS_EX_RTLREADING	If the shell language is Hebrew, Arabic, or another language that supports reading order alignment, the window text is displayed using Right to Left reading-order properties. For other languages, the style is ignored and not treated as an error.
WS_EX_STATICEDGE	Creates a window with a three-dimensional border style intended to be used for items that do not accept user input.
WS_EX_TOOLWINDOW	Creates a tool window; that is, a window intended to be used as a floating toolbar. A tool window has a title bar that is shorter than a normal title bar, and the window title is drawn using a smaller font. A tool window does not appear in the taskbar or in the dialog that appears when the user presses ALT+TAB. If a tool window has a system menu, its icon is not displayed on the title bar. However, you can display the system menu by right-clicking or by typing ALT+SPACE.
WS_EX_TOPMOST	Specifies that a window created with this style should be placed above all non-topmost windows and should stay above them, even when the window is deactivated. To add or remove this style, use the SetWindowPos function.
WS_EX_TRANSPARENT	Specifies that a window created with this style is to be transparent. That is, any windows that are beneath the window are not obscured by the window. A window created with this style receives WM_PAINT messages only after all sibling windows beneath it have been updated.
WS_EX_WINDOWEDGE	Specifies that a window has a border with a raised edge.

Using the WS_EX_RIGHT style for static or edit controls has the same effect as using the SS_RIGHT or ES_RIGHT style, respectively. Using this style with button controls has the same effect as using BS_RIGHT and BS_RIGHTBUTTON styles.

lpClassName

Points to a null-terminated string or is an integer atom. If lpClassName is an atom, it must be a global atom created by a previous call to GlobalAddAtom. The atom, a 16-bit value less than 0xC000, must be in the low-order word of lpClassName; the high-order word must be zero.

If lpClassName is a string, it specifies the window class name. The class name can be any name registered with the RegisterClass function or any of the predefined control-class names.

lpWindowName

Points to a null-terminated string that specifies the window name.

dwStyle

Specifies the style of the window being created. For a list of the window styles that can be specified in dwStyle, see CreateWindow.

x

Specifies the initial horizontal position of the window. For an overlapped or pop-up window, the x parameter is the initial x-coordinate of the window’s upper-left corner, in screen coordinates. For a child window, x is the x-coordinate of the upper-left corner of the window relative to the upper-left corner of the parent window’s client area.

If x is set to CW_USEDEFAULT, Windows selects the default position for the window’s upper-left corner and ignores the y parameter. CW_USEDEFAULT is valid only for overlapped windows; if it is specified for a pop-up or child window, the x and y parameters are set to zero.

y

Specifies the initial vertical position of the window. For an overlapped or pop-up window, the y parameter is the initial y-coordinate of the window’s upper-left corner, in screen coordinates. For a child window, y is the initial y-coordinate of the upper-left corner of the child window relative to the upper-left corner of the parent window’s client area. For a list box, y is the initial y-coordinate of the upper-left corner of the list box’s client area relative to the upper-left corner of the parent window’s client area.

If an overlapped window is created with the WS_VISIBLE style bit set and the x parameter is set to CW_USEDEFAULT, Windows ignores the y parameter.

nWidth

Specifies the width, in device units, of the window. For overlapped windows, nWidth is the window’s width, in screen coordinates, or CW_USEDEFAULT. If nWidth is CW_USEDEFAULT, Windows selects a default width and height for the window; the default width extends from the initial x-coordinates to the right edge of the screen; the default height extends from the initial y-coordinate to the top of the icon area. CW_USEDEFAULT is valid only for overlapped windows; if CW_USEDEFAULT is specified for a pop-up or child window, the nWidth and nHeight parameter are set to zero.

nHeight

Specifies the height, in device units, of the window. For overlapped windows, nHeight is the window’s height, in screen coordinates. If the nWidth parameter is set to CW_USEDEFAULT, Windows ignores nHeight.

hWndParent

Identifies the parent or owner window of the window being created. To create a child window or an owned window, supply a valid window handle. To create a message-only window, supply HWND_MESSAGE or a handle to an existing message-only window. This parameter is optional for pop-up windows.

hMenu

Identifies a menu, or specifies a child-window identifier, depending on the window style. For an overlapped or pop-up window, hMenu identifies the menu to be used with the window; it can be NULL if the class menu is to be used. For a child window, hMenu specifies the child-window identifier, an integer value used by a dialog box control to notify its parent about events. The application determines the child-window identifier; it must be unique for all child windows with the same parent window.

hInstance

Identifies the instance of the module to be associated with the window.

lpParam

A pointer to a value to be passed to the window through the CREATESTRUCT structure passed in the lParam parameter the WM_CREATE message. If an application calls CreateWindow to create a multiple document interface (MDI) client window, lpParam must point to a CLIENTCREATESTRUCT structure.

Return Values

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

If the function fails, the return value is NULL. To get extended error information, call GetLastError.

Remarks

The CreateWindowEx function sends WM_NCCREATE, WM_NCCALCSIZE, and WM_CREATE messages to the window being created.

For information about the window control classes, window styles, and control styles used with this function, see the description of the CreateWindow function.

Windows 95: The system can support a maximum of 16,364 window handles.

See Also

CLIENTCREATESTRUCT, CREATESTRUCT, CreateWindow, GlobalAddAtom, RegisterClass, SetWindowPos, WM_CREATE, WM_NCCALCSIZE, WM_NCCREATE, WM_PAINT, WM_PARENTNOTIFY