C# Signature:

/// <summary>
/// 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.
/// </summary>
/// <param name="dwExStyle">Specifies the extended window style of the window
/// being created.</param>
/// <param name="lpClassName">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.</param>
/// <param name="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.
/// 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". </param>
/// <param name="dwStyle">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.</param>
/// <param name="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.</param>
/// <param name="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.
/// <para>If an overlapped window is created with the WS_VISIBLE style bit
/// set and the x parameter is set to CW_USEDEFAULT, then the y parameter
/// determines how the window is shown. If the y parameter is CW_USEDEFAULT,
/// then the window manager calls ShowWindow with the SW_SHOW flag after
/// the window has been created. If the y parameter is some other value,
/// then the window manager calls ShowWindow with that value as the
/// nCmdShow parameter.</para></param>
/// <param name="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.</param>
/// <param name="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.</param>
/// <param name="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.
/// <para>Windows 2000/XP: To create a message-only window, supply
/// HWND_MESSAGE or a handle to an existing message-only window.</para></param>
/// <param name="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.</param>
/// <param name="hInstance">Handle to the instance of the module to be
/// associated with the window.</param>
/// <param name="lpParam">Pointer to a value to be passed to the window
/// through the CREATESTRUCT structure (lpCreateParams member) pointed to
/// by the lParam param of the WM_CREATE message. This message is sent to
/// the created window by this function before it returns.
/// <para>If an application calls CreateWindow to create a MDI client
/// window, lpParam should point to a CLIENTCREATESTRUCT structure. If an
/// MDI client window calls CreateWindow to create an MDI child window,
/// lpParam should point to a MDICREATESTRUCT structure. lpParam may be
/// NULL if no additional data is needed.</para></param>
/// <returns>If the function succeeds, the return value is a handle to the
/// new window.
/// <para>If the function fails, the return value is NULL. To get extended
/// error information, call GetLastError.</para>
/// <para>This function typically fails for one of the following reasons:</para>
/// <list type="">
/// <item>an invalid parameter value</item>
/// <item>the system class was registered by a different module</item>
/// <item>The WH_CBT hook is installed and returns a failure code</item>
/// <item>if one of the controls in the dialog template is not registered,
/// or its window window procedure fails WM_CREATE or WM_NCCREATE</item></returns>
[DllImport("user32.dll")]
static extern IntPtr CreateWindowEx(
   uint dwExStyle,
   string lpClassName,
   string lpWindowName,
   uint dwStyle,
   int x,
   int y,
   int nWidth,
   int nHeight,
   IntPtr hWndParent,
   IntPtr hMenu,
   IntPtr hInstance,
   IntPtr lpParam);

VB Signature:

<DllImport("user32.dll", CharSet:=CharSet.Auto)> _
Private Shared Function CreateWindowEx( _
     ByVal dwExStyle As UInteger, _
     ByVal lpClassName As String, _
     ByVal lpWindowName As String, _
     ByVal dwStyle As WindowStyles, _
     ByVal x As Integer, _
     ByVal y As Integer, _
     ByVal nWidth As Integer, _
     ByVal nHeight As Integer, _
     ByVal hWndParent As IntPtr, _
     ByVal hMenut As IntPtr, _
     ByVal hInstancet As IntPtr, _
     ByVal lpParamt As IntPtr) As IntPtr
End Function

Notes:

Returns a handle (IntPtr) for the window created.

Tips & Tricks:

Please add some!

Sample Code:

Please add some!

Alternative Managed API:

Instantiate a System.Windows.Forms.Form and set its properties to control its style.

The System.Windows.Forms.NativeWindow class can be used to encapsulate a window handle. It provides properties and methods that can be used to perform the same behavior as the CreateWindowEx method.