style

Specifies the class style(s). Styles can be combined by using the bitwise OR (|) operator. This member can be any combination of the following values.

Value	Description
CS_DBLCLKS	Sends double-click messages to the window procedure when the user double-clicks the mouse while the cursor is within a window belonging to the class.
CS_HREDRAW	Redraws the entire window if a movement or size adjustment changes the width of the client area.
CS_NOCLOSE	Disables Closeon the windowmenu.
CS_PARENTDC	Sets the clipping region of the child window to that of the parent window so that the child can draw on the parent. A window with the CS_PARENTDC style bit receives a regular device context from the system's cache of device contexts. It does not give the child the parent's device context or device context settings. Specifying CS_PARENTDC enhances an application's performance.
CS_VREDRAW	Redraws the entire window if a movement or size adjustment changes the height of the client area.

lpfnWndProc

Long pointer to the window procedure. You must use the CallWindowProcfunction to call the window procedure. For more information, see WindowProc.

cbClsExtra

Specifies the number of extra bytes to allocate following the window-class structure. The system initializes the bytes to zero.

cbWndExtra

Specifies the number of extra bytes to allocate following the window instance. The system initializes the bytes to zero. If an application uses WNDCLASSto register a dialog box created by using the CLASSdirective in the resource file, the application must set cbWndExtraequal to the value obtained for cbWndExtrawhen the application calls the GetClassInfofunction on the system DIALOG class. This value is the number of extra bytes the OS requires for each dialog box.

hInstance

Handle to the instance that the window procedure of this class is within.

hIcon

Unsupported; set to NULL. An application must draw an icon whenever the user minimizes the application window.

hCursor

Handle to the class cursor. This member must be a handle to a cursor resource. If this member is NULL, an application must explicitly set the cursor shape whenever the mouse moves into the application's window.

hbrBackground

Handle to the class background brush. This member can be a handle to the physical brush to be used for painting the background, or it can be a color value. A color value must be one of the following standard system colors (the value 1 must be added to the chosen color). If a color value is given, you must convert it to one of the following HBRUSHtypes:

COLOR_ACTIVEBORDER	COLOR_HIGHLIGHTTEXT
COLOR_ACTIVECAPTION	COLOR_INACTIVEBORDER
COLOR_APPWORKSPACE	COLOR_INACTIVECAPTION
COLOR_BACKGROUND	COLOR_MENU
COLOR_BTNFACE	COLOR_MENUTEXT
COLOR_BTNSHADOW	COLOR_SCROLLBAR
COLOR_BTNTEXT	COLOR_WINDOW
COLOR_CAPTIONTEXT	COLOR_WINDOWFRAME
COLOR_GRAYTEXT	COLOR_WINDOWTEXT
COLOR_HIGHLIGHT

The system automatically deletes class background brushes when the class is freed. An application should not delete these brushes, because a class may be used by multiple instances of an application.

When this member is NULL, an application must paint its own background whenever it is requested to paint in its client area. To determine whether the background must be painted, an application can either process the WM_ERASEBKGND message or test the fErasemember of the PAINTSTRUCTstructure filled by the BeginPaintfunction.

lpszMenuName

Long pointer to a null-terminated character string that specifies the resource name of the class menu, as the name appears in the resource file. If you use an integer to identify the menu, use the MAKEINTRESOURCEmacro. If this member is NULL, windows belonging to this class have no default menu.

lpszClassName

Either a long pointer to a null-terminated string or an atom. If this member is an atom, it must be a global atom created by a previous call to the GlobalAddAtomfunction. The atom, a 16-bit value, must be in the low-order word of lpszClassName; the high-order word must be zero.

If lpszClassNameis a string, it specifies the window class name.

The following members are restricted.

• cbClsExtramust be a multiple of four.
  
  
• cbWndExtramust be a multiple of four.
  
  
• Unless you are using the Windows Embedded CE Iconcurs component, which supports mouse cursors on appropriate target platforms, the hCursormember must be set to NULL.
  
  
• lpszMenuNameis not supported and must be NULL.
  
  
• lpszClassNamemust be a string. Atoms are not supported.
  
  
• In Windows CE 1.0, the stylemember can only be the CS_DBLCLKS value.
  
  
• In Windows CE 2.0 and later, the stylemember can be the following values:
  
  
  • CS_DBLCLKS
    
    
  • CS_HREDRAW
    
    
  • CS_IME
    
    
  • CS_NOCLOSE
    
    
  • CS_PARENTDC
    
    
  • CS_VREDRAW
    
    

In Windows Embedded CE, all window classes are process global.

Note:
The technique of putting a class name and DLL in the registry and having a DLL automatically loaded is not supported.