CMainFrame
CMainFrame is a class name frequently used in applications built with the Microsoft Foundation Class (MFC) library to implement the program’s main frame window. It typically derives from CFrameWnd or CFrameWndEx and serves as the top-level container for the application's user interface, hosting elements such as the menu bar, toolbars, and status bar, and coordinating with the document/view architecture.
In standard MFC SDI or MDI applications, CMainFrame is created early in the application lifecycle and is
CMainFrame interacts with the document and view components by hosting the primary view or views that present
Variations exist across projects; some code bases rename the class or extend it (for example, CMainFrameEx)