The Microsoft Windows CE operating system combines the Microsoft Win32® application programming interface (API), user interface (UI), and Graphics Device Interface (GDI) libraries into the Graphics, Windowing, and Events Subsystem (GWES) module (Gwes.exe). GWES is the interface between the user, your application, and the OS.
GWES supports all the windows, dialog boxes, controls, menus, and resources that make up the Windows CE UI. This UI enables users to control applications. GWES also provides information to the user in the form of bitmaps, carets, cursors, text, and icons.
Even Windows CE–based platforms that lack a graphical UI use GWES basic windowing and messaging capabilities and power management functions.