The system provides standard metrics and settings for user interface aspects, such as colors, fonts, border width, and drag rectangle (used to detect the start of a drag operation). The system also notifies running applications when its settings change. When your application starts up, query the system to set your application's user interface to match the system parameters to ensure visual and operational consistency. Also, design your application to adjust itself appropriately when the system notifies it of changes to these settings.
Note 
The GetSystemMetrics, GetSysColor, and SystemParameters-Info functions and the WM_SETTINGS-CHANGE message are important to consider when supporting standard system settings. For more information about these system interfaces, see the documentation included in the Win32 SDK.