WM_SYSCOLORCHANGE Must Be Sent to Windows 95 Common Controls

• Microsoft Win32 Application Programming Interface (API) included with:

      - Microsoft Windows NT version 3.51
      - Microsoft Windows 95 version 4.0
      - Microsoft Win32s version 1.3
  

SUMMARY

You must ensure that applications that use the new common controls introduced in Windows 95 and Windows NT version 3.51 forward the WM_SYSCOLORCHANGE message to the controls.

MORE INFORMATION

Windows 95 makes it very easy for the user to change the colors of common user interface objects, therefore it is critical that applications not rely on particular colors being constant. When the user changes the color settings, Windows 95 will send a WM_SYSCOLORCHANGE message to all top level windows. Because this message is sent only to top level windows, the common controls will not be notified of the color change unless the application forwards the WM_SYSCOLORCHANGE message to the control.

An example of why this is important is the toolbar control. If the color settings are such that the "3D Objects" color is set to light gray, the toolbar will create its buttons to light gray. However if the WM_SYSCOLORCHANGE message is not forwarded to the toolbar and the 3D Object color is changed to blue, the toolbar buttons will remain light gray while all the other buttons in the system change to blue.