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CreateWindowEx

The CreateWindowEx function creates an overlapped, pop-up, or child window with an extended window 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,  // registered class name
  LPCTSTR lpWindowName, // 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,          // menu handle or child identifier
  HINSTANCE hInstance,  // handle to application instance
  LPVOID lpParam        // window-creation data
);

Parameters

dwExStyle
[in] Specifies the extended window style of the window being created. This parameter can be one or more 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_COMPOSITED Whistler: Paints all descendants of a window in bottom-to-top painting order using double-buffering. For more information, see Remarks.
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 The window itself contains child windows that should take part in dialog box navigation. If this style is specified, the dialog manager recurses into children of this window when performing navigation operations such as handling the TAB key, an arrow key, or a keyboard mnemonic.
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_LAYERED Windows 2000: Creates a layered window. Note that this cannot be used for child windows.
WS_EX_LAYOUTRTL Windows 2000 and the Arabic and Hebrew versions of Windows 98 and Windows Me: Creates a window whose horizontal origin is on the right edge. Increasing horizontal values advance to the left.
WS_EX_LEFT Creates a window that 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.
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_NOACTIVATE Windows 2000: A top-level window created with this style does not become the foreground window when the user clicks it. The system does not bring this window to the foreground when the user minimizes or closes the foreground window.

To activate the window, use the SetActiveWindow or SetForegroundWindow function.

The window does not appear on the taskbar by default. To force the window to appear on the taskbar, use the WS_EX_APPWINDOW style.

WS_EX_NOINHERITLAYOUT Windows 2000: A window created with this style does not pass its window layout to its child windows.
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.
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.
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
[in] Pointer to a null-terminated string or a class atom created by a previous call to the RegisterClass or RegisterClassEx function. The atom 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 RegisterClass or RegisterClassEx, provided that the module that registers the class is also the module that creates the window. The class name can also be any of the predefined system class names.

lpWindowName
[in] 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. When creating a static control with the SS_ICON style, use lpWindowName to specify the icon name or identifier. To specify an identifier, use the syntax "#num".

dwStyle
[in] Specifies the style of the window being created. This parameter can be a combination of window styles, plus the control styles indicated in the Remarks section.
x
[in] 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
[in] 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
[in] 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
[in] 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
[in] 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 2000: To create a message-only window, supply HWND_MESSAGE or a handle to an existing message-only window.

hMenu
[in] 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
Windows 95/98: [in] Handle to the instance of the module to be associated with the window.

Windows NT/2000: This value is ignored.

lpParam
[in] 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.

This function typically fails for one of the following reasons:

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.

Class Meaning
BUTTON Designates a small rectangular child window that represents a button the user can click to turn it on or off. Button controls can be used alone or in groups, and they can either be labeled or appear without text. Button controls typically change appearance when the user clicks them. For more information, see Buttons.

For a table of the button styles you can specify in the dwStyle parameter, see Button Styles.

COMBOBOX Designates a control consisting of a list box and a selection field similar to an edit control. When using this style, an application should either display the list box at all times or enable a drop-down list box. If the list box is visible, typing characters into the selection field highlights the first list box entry that matches the characters typed. Conversely, selecting an item in the list box displays the selected text in the selection field. For more information, see Combo Boxes.

For a table of the combo box styles you can specify in the dwStyle parameter, see Combo Box Styles.

EDIT Designates a rectangular child window into which the user can type text from the keyboard. The user selects the control and gives it the keyboard focus by clicking it or moving to it by pressing the TAB key. The user can type text when the edit control displays a flashing caret; use the mouse to move the cursor, select characters to be replaced, or position the cursor for inserting characters; or use the BACKSPACE key to delete characters. For more information, see Edit Controls.

For a table of the edit control styles you can specify in the dwStyle parameter, see Edit Control Styles.

LISTBOX Designates a list of character strings. Specify this control whenever an application must present a list of names, such as filenames, from which the user can choose. The user can select a string by clicking it. A selected string is highlighted, and a notification message is passed to the parent window. For more information, see List Boxes.

For a table of the list box styles you can specify in the dwStyle parameter, see List Box Styles.

MDICLIENT Designates an MDI client window. This window receives messages that control the MDI application's child windows. The recommended style bits are WS_CLIPCHILDREN and WS_CHILD. Specify the WS_HSCROLL and WS_VSCROLL styles to create an MDI client window that allows the user to scroll MDI child windows into view. For more information, see Multiple Document Interface.
RichEdit Designates a Rich Edit version 1.0 control. This window lets the user view and edit text with character and paragraph formatting, and can include embedded COM objects. For more information, see Rich Edit Controls.

For a table of the rich edit control styles you can specify in the dwStyle parameter, see Rich Edit Control Styles.

RICHEDIT_CLASS Designates a Rich Edit version 2.0 control. This controls let the user view and edit text with character and paragraph formatting, and can include embedded COM objects. For more information, see Rich Edit Controls.

For a table of the rich edit control styles you can specify in the dwStyle parameter, see Rich Edit Control Styles.

SCROLLBAR Designates a rectangle that contains a scroll box and has direction arrows at both ends. The scroll bar sends a notification message to its parent window whenever the user clicks the control. The parent window is responsible for updating the position of the scroll box, if necessary. For more information, see Scroll Bars.

For a table of the scroll bar control styles you can specify in the dwStyle parameter, see Scroll Bar Control Styles.

STATIC Designates a simple text field, box, or rectangle used to label, box, or separate other controls. Static controls take no input and provide no output. For more information, see Static Controls.

For a table of the static control styles you can specify in the dwStyle parameter, see Static Control Styles.


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

Windows 2000: The WS_EX_NOACTIVATE value for dwExStyle prevents foreground activation by the system. To prevent queue activation when the user clicks on the window, you must process the WM_MOUSEACTIVATE message appropriately. To bring the window to the foreground or to activate it programmatically, use SetForegroundWindow or SetActiveWindow. Returning FALSE to WM_NCACTIVATE prevents the window from losing queue activation. However, the return value is ignored at activation time.

Whistler: With WS_EX_COMPOSITED set, all descendants of a window get bottom-to-top painting order using double-buffering. Bottom-to-top painting order allows a descendent window to have translucency (alpha) and transparency (color-key) effects, but only if the descendent window also has the WS_EX_TRANSPARENT bit set. Double-buffering allows the window and its descendents to be painted without flicker.

Requirements

  Windows NT/2000: Requires Windows NT 3.1 or later.
  Windows 95/98: Requires Windows 95 or later.
  Header: Declared in Winuser.h; include Windows.h.
  Library: Use User32.lib.
  Unicode: Implemented as Unicode and ANSI versions on Windows NT/2000.

See Also

Windows Overview, Window Functions, CLIENTCREATESTRUCT, CREATESTRUCT, CreateWindow, EnableWindow, RegisterClass, RegisterClassEx, SetActiveWindow, SetForegroundWindow, SetWindowLong, SetWindowPos, ShowWindow, WM_CREATE, WM_NCCALCSIZE, WM_NCCREATE, WM_PAINT, WM_PARENTNOTIFY