Messages are processed by window and dialog procedures.
Every window has a window procedure. Windows can also be combined into standard windows or dialog boxes. These are special cases of groups of windows that also have their own procedures. A window or dialog procedure must be capable of processing any message. This can be achieved by delegating some message types to the default window, or dialog, procedures by use of the WinDefWindowProc and WinDefDlgProc functions respectively.
Control windows are a special type of child windows. They take the form of objects such as buttons, scroll bars, list boxes, and text entry fields. These child windows process mouse and keyboard input and notify its owner of significant input events. Procedures for these child window controls are inside the Presentation Manager and are often called system-provided window procedures.
All messages have the same form as QMSG. structure.
Message Types
There are two types of window procedure message processing:
These types are described in Default Window and Dialog Procedure Message Processing and Control Window Message Processing. The messages are described in the message groups found on the Contents.