CS_SAVEBITS Class Style Bit

• Microsoft Windows Software Development Kit (SDK) versions 3.0 and 3.1
• Microsoft Win32 Application Programming Interface (API) included with:

      - Microsoft Windows NT versions 3.5 and 3.51
      - Microsoft Windows 95 version 4.0
  

SUMMARY

If the CS_SAVEBITS style is included when registering a pop-up window, a bitmap copy of the screen image that the window will obscure is saved in memory when the window is displayed.

The bitmap is redisplayed at its original location and no WM_PAINT messages are sent to the obscured windows if the following is true when the window is removed from the display:

• The memory used by the saved bitmap has not been discarded.
• Other screen actions have not invalidated the image that has been stored.

The window will take longer to be displayed because memory needs to be allocated. The bitmap also needs to be copied over each time the window is shown.

Use should be restricted to small windows that come up and are then removed before much other screen activity takes place. Any memory calls that will discard all discardable memory, and any actions that take place "under" the window, will invalidate the bitmap.