This unit provides the interface to the Windows common controls.
Common controls are a set of windows that are supported
by the common control library, which is a dynamic-link library
(DLL) included with the Microsoft® Windows®
Like other control windows, a common control is a child window
that an application uses in conjunction with another window
to perform input and output (I/O) tasks.
For more info look the "Common Controls" in WIN32.HLP.