A control bar is a window that is usually aligned to the left or right of a frame window. It may contain child items that are either HWND-based controls, which are Windows windows that generate and respond to Windows messages, or non-HWND-based items, which are not windows and are managed by application code or framework code. List boxes and edit controls are examples of HWND-based controls; status-bar panes and bitmap buttons are examples of non-HWND-based controls.
Control-bar windows are usually child windows of a parent frame window and are usually siblings to the client view or MDI client of the frame window. A CControlBar object uses information about the parent window's client rectangle to position itself. It then informs the parent window as to how much space remains unallocated in the parent window's client area.
For more information on CControlBar, see: