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Q33096: INFO: Drawing Outside a Window’s Client Area

Article: Q33096
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.1,95; winnt:3.5,3.51
Operating System(s): 
Keyword(s): kbOSWinNT350 kbOSWinNT351 kbOSWin95 kbSDKWin16
Last Modified: 11-MAY-2001

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The information in this article applies to:

- Microsoft Windows Software Development Kit (SDK) 3.1 
- Microsoft Win32 Application Programming Interface (API), used with:
   - Microsoft Windows NT Server versions 3.5, 3.51 
   - Microsoft Windows NT Workstation versions 3.5, 3.51 
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SUMMARY
=======

When an application uses the BeginPaint or GetDC function to obtain a device
context (DC) for its client window and draws into this DC, Windows clips the
output to the edge of the client window. While this is usually the desired
effect, there are circumstances where an application draws outside the client
area of its window.

MORE INFORMATION
================

The GetWindowDC function provides a DC that allows an application to draw
anywhere within its window, including the nonclient area.

In the Windows environment, the display is a scarce resource that is shared by
all applications running in the system. Most of the time, an application should
restrict its output to the area of the screen it has been assigned by the user.
However, an application can use the CreateDC function to obtain a DC for the
entire display, as follows:

     hDC = CreateDC("DISPLAY", NULL, NULL, NULL);

Device contexts are another scarce resource in the Windows environment. When an
application creates a DC in response to a WM_PAINT message, it must call the
DeleteDC function to free the DC before it completes processing of the message.

Painting in the nonclient area of a window is not recommended. If an application
changes the nonclient area of its window, the user can become confused because
the familiar Windows controls change appearance or are not available. An
application should not corrupt other windows on the display.

Additional query words: 3.00 3.10 3.50 4.00

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Keywords          : kbOSWinNT350 kbOSWinNT351 kbOSWin95 kbSDKWin16 
Technology        : kbAudDeveloper kbSDKSearch kbWin32sSearch kbWin32API kbWinSDKSearch
Version           : WINDOWS:3.1,95; winnt:3.5,3.51
Issue type        : kbinfo

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