The mouse into the graphic controls the client area sometimes display the cursor for the left and right arrows show the normal cursor sometimes don't know why

CodePudding user response:

WNDCLASS
The WNDCLASS structure contains The window class attributes that are registered by The RegisterClass function.

This structure has had been superseded by the modifed WNDCLASSEX structure 2 have the RegisterClassEx function. You can still use WNDCLASS and RegisterClass if You do not need to set the small icon associated with the window class.

Typedef struct _WNDCLASS {
UINT style;
WNDPROC lpfnWndProc;
Int cbClsExtra;
Int cbWndExtra;
HANDLE hInstance;
HICON HICON;
HCURSOR HCURSOR;
HBRUSH hbrBackground;
LPCTSTR lpszMenuName;
LPCTSTR lpszClassName;
} WNDCLASS;

Members
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 Action
CS_BYTEALIGNCLIENT Aligns the window's client area on the byte boundary (in the x direction). This style affects the width of the window and its horizontal position on the display.
CS_BYTEALIGNWINDOW Aligns a window on a byte boundary (in the x direction). This style affects the width of the window and its horizontal position on the display.
CS_CLASSDC Allocates one device context to be Shared by all Windows in the class. Because the window classes are process specific, it is possible for multiple threads of an application to create a window of the same class. It is also possible for the threads to attempt to use the device context simultaneously. When this happens, the system allows only one thread to successfully finish its drawing operation. For more information, seeDevice Contexts.
CS_DBLCLKS Sends a double - click the messages to the window procedure when the user double - on the mouse while the cursor is within a window belonging to the class.
CS_GLOBALCLASS Allows an application to create a window of the class chopped of the value of the hInstance parameter passed to the CreateWindow or CreateWindowEx function. If you do not specify this style, the hInstance parameter passed to the CreateWindow (or CreateWindowEx) function must be the same as the hInstance parameter passed to the RegisterClass function.
You can create a global class by creating the window class in a dynamic - link library (DLL) and listing the name of the DLL in the registry under the following keys:
HKEY_LOCAL_MACHINE \ Software
, Microsoft, Windows NT,
CurrentVersion \ Windows \ AppInit_DLLs
Whenever a process starts, the system loads the specified DLLs in the context of the newly started the process before calling the entry - point function in that process, the DLL must register the class during its initialization procedure and must specify the CS_GLOBALCLASS style.
CS_HREDRAW Redraws the window if - a movement or the size adjustment changes the width of the client area.
CS_NOCLOSE Disables Close on the window menu.
CS_OWNDC Allocates a unique device context for each window in the class.
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 difference the child the parent' s device context or device context Settings. Specifying CS_PARENTDC enhances an application 's performance. For more information, seeDevice contexts.
CS_SAVEBITS Saves, as a bitmap, the portion of the screen image obscured by a window. The system uses the saved bitmap to re-create the screen image when the window is removed. The system displays the bitmap at its original location and does not sendWM_PAINT messages to windows obscured by the window if the memory used by the bitmap has not been discarded and if other screen actions have not invalidated the stored image. This style is useful for small windows (for example, menus or dialog boxes) that are displayed briefly and then removed before other screen activity takes place. This style increases the time required to display the window, because the system must first allocate memory to store the bitmap.
CS_VREDRAW Redraws the window if - a movement or the size adjustment changes the height of the client area.


LpfnWndProc
Pointer to the window procedure. You must use the CallWindowProc function to call the window procedure. For more information, see WindowProc.
CbClsExtra
Specifies the number of extra bytes to the allocate following the window - the class structure. The system initializes the bytes to zero.
CbWndExtra
nullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnull