CreateWindowEx

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 visible.
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	The 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 should not be painted until siblings beneath the window (that were created by the same thread) have been painted. The window appears transparent because the bits of underlying sibling windows have already been painted. To achieve transparency without these restrictions, use the SetWindowRgn function.
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

Pointer 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 RegisterClassEx function or any of the predefined control-class names.

lpWindowName

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

If the window style specifies a title bar, the window title pointed to by lpWindowName is displayed in the title bar. When using CreateWindow to create controls, such as buttons, check boxes, and static controls, use lpWindowName to specify the text of the control.

dwStyle

Specifies the style of the window being created. This parameter can be a combination of the following window styles, plus the control styles indicated in the Remarks section.

Style	Meaning
WS_BORDER	Creates a window that has a thin-line border.
WS_CAPTION	Creates a window that has a title bar (includes the WS_BORDER style).
WS_CHILD	Creates a child window. This style cannot be used with the WS_POPUP style.
WS_CHILDWINDOW	Same as the WS_CHILD style.
WS_CLIPCHILDREN	Excludes the area occupied by child windows when drawing occurs within the parent window. This style is used when creating the parent window.
WS_CLIPSIBLINGS	Clips child windows relative to each other; that is, when a particular child window receives a WM_PAINT message, the WS_CLIPSIBLINGS style clips all other overlapping child windows out of the region of the child window to be updated. If WS_CLIPSIBLINGS is not specified and child windows overlap, it is possible, when drawing within the client area of a child window, to draw within the client area of a neighboring child window.
WS_DISABLED	Creates a window that is initially disabled. A disabled window cannot receive input from the user.
WS_DLGFRAME	Creates a window that has a border of a style typically used with dialog boxes. A window with this style cannot have a title bar.
WS_GROUP	Specifies the first control of a group of controls. The group consists of this first control and all controls defined after it, up to the next control with the WS_GROUP style. The first control in each group usually has the WS_TABSTOP style so that the user can move from group to group. The user can subsequently change the keyboard focus from one control in the group to the next control in the group by using the direction keys.
WS_HSCROLL	Creates a window that has a horizontal scroll bar.
WS_ICONIC	Creates a window that is initially minimized. Same as the WS_MINIMIZE style.
WS_MAXIMIZE	Creates a window that is initially maximized.
WS_MAXIMIZEBOX	Creates a window that has a Maximize button. Cannot be combined with the WS_EX_CONTEXTHELP style. The WS_SYSMENU style must also be specified.
WS_MINIMIZE	Creates a window that is initially minimized. Same as the WS_ICONIC style.
WS_MINIMIZEBOX	Creates a window that has a Minimize button. Cannot be combined with the WS_EX_CONTEXTHELP style. The WS_SYSMENU style must also be specified.
WS_OVERLAPPED	Creates an overlapped window. An overlapped window has a title bar and a border. Same as the WS_TILED style.
WS_OVERLAPPEDWINDOW	Creates an overlapped window with the WS_OVERLAPPED, WS_CAPTION, WS_SYSMENU, WS_THICKFRAME, WS_MINIMIZEBOX, and WS_MAXIMIZEBOX styles. Same as the WS_TILEDWINDOW style.
WS_POPUP	Creates a pop-up window. This style cannot be used with the WS_CHILD style.
WS_POPUPWINDOW	Creates a pop-up window with WS_BORDER, WS_POPUP, and WS_SYSMENU styles. The WS_CAPTION and WS_POPUPWINDOW styles must be combined to make the window menu visible.
WS_SIZEBOX	Creates a window that has a sizing border. Same as the WS_THICKFRAME style.
WS_SYSMENU	Creates a window that has a window menu on its title bar. The WS_CAPTION style must also be specified.
WS_TABSTOP	Specifies a control that can receive the keyboard focus when the user presses the tab key. Pressing the tab key changes the keyboard focus to the next control with the WS_TABSTOP style.
WS_THICKFRAME	Creates a window that has a sizing border. Same as the WS_SIZEBOX style.
WS_TILED	Creates an overlapped window. An overlapped window has a title bar and a border. Same as the WS_OVERLAPPED style.
WS_TILEDWINDOW	Creates an overlapped window with the WS_OVERLAPPED, WS_CAPTION, WS_SYSMENU, WS_THICKFRAME, WS_MINIMIZEBOX, and WS_MAXIMIZEBOX styles. Same as the WS_OVERLAPPEDWINDOW style.
WS_VISIBLE	Creates a window that is initially visible.
WS_VSCROLL	Creates a window that has a vertical scroll bar.

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, the system 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, the system 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, the system 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, the system ignores nHeight.

hWndParent

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

Windows NT 5.0 and later: To create a message-only window, supply HWND_MESSAGE or a handle to an existing message-only window.

hMenu

Handle to 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

Handle to 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 a 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 on controlling whether the Taskbar displays a button for the created window, see Visibility of Taskbar Buttons.

The following predefined control classes can be specified in the lpClassName parameter. Note the corresponding control styles you can use in the dwStyle parameter.

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

Windows CE: Windows CE does not support stand alone menu bars. The hMenu parameter must be NULL, unless it is used as a child-window identifier.

Windows CE versions 2.0 and later support the following two extended window styles:

WS_EX_NOACTIVATE

A top level window created with this style cannot be activated. If a child window has this style, tapping it will not cause its top-level parent to be activated. A window that has this style will receive stylus events, but neither it nor its child windows can get the focus.

WS_EX_NOANIMATION

A window created with this style does not show animated exploding and imploding rectangles, and does not have a button on the taskbar.

The following dwExStyle flags are not supported.

Windows CE 1.0 does not support the WS_EX_TOPMOST style. Versions 2.0 and later do.

The following dwStyle flags are not supported.

All windows implicitly have the WS_CLIPSIBLINGS and WS_CLIPCHILDREN styles.

Windows CE 1.0 does not support owned windows, except for dialog boxes. If the hwndParent parameter is not NULL, the window is implicitly given the WS_CHILD style.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Requires version 1.0 or later.
  Header: Declared in winuser.h.
  Import Library: Use user32.lib.
  Unicode: Implemented as Unicode and ANSI versions on Windows NT.

See Also

Windows Overview, Window Functions, CLIENTCREATESTRUCT, CREATESTRUCT, CreateWindow, GlobalAddAtom, RegisterClassEx, SetWindowPos, WM_CREATE, WM_NCCALCSIZE, WM_NCCREATE, WM_PAINT, WM_PARENTNOTIFY