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                           Using Control Windows
 
Control windows can be used in dialog windows and standard-frame or client
windows.
 
To use a control window in a dialog window, an application defines the
control. A dialog template typically includes several control windows as
part of the dialog template in its resource file. Then, when the dialog
resource is loaded and displayed, control windows are automatically
displayed as part of the dialog window. The application can then send
messages to the control window to change its state. The dialog-window
procedure defined by an application receives notification messages from the
control window. The nature of these messages depends on the specific type of
control window.
 
To use a control window in a non-dialog window, an application must call the
WinCreateWindow function using the appropriate window-class specification.
An application usually specifies one of its client windows as the owner of
the control window. Therefore, the client-window procedure receives
notification messages from the control window. In some cases where a control
is owned by the frame window (such as a menu control), the notification
messages to the frame are passed on to the client window.
 
Creating a Custom Control Window
 
MS OS/2 provides several predefined control-window classes. You can create
custom-control windows to fit specific purposes in the an application by
doing the following:
 
♦  Using the user-drawn buttons, list boxes, and menus
 
♦  Subclassing an existing control-window class
 
♦  Registering and implementing a window class from scratch
 
Buttons, list boxes, and menus have an optional style designation that marks
them as "user-drawn." This means that the owner window of the control with
this style receives a message whenever the control must be drawn. (If the
owner window is a frame window, it sends owner-drawn messages to its client
windows, which should be handled by the client-window procedure.) This
allows you to alter the appearance of a control window. For buttons, the
owner-drawn style affects the drawing of the entire control. For menus and
list boxes, the owner draws the individual items within the control, and the
system draws the external outline of the control.
 
Subclassing an existing control window is an easy way to make custom
controls. When you subclass an existing control window, you only alter those
behaviors you want to change, letting all other messages through to the
original control-window procedure.
 
The techniques for defining a custom control window are the same as those
used in creating a client-window class. However, if you are creating your
own custom-control window class, be sure it can send and receive
"Control-window messages."
 
If you create a custom control-window class by subclassing a control class
or by creating a window class from scratch, you can use its class name in
the dialog template just like a predefined window-class constant. For
example, if you define and register a window class called "MyControlClass"
in an application, you can define a dialog window containing a control
window using the following resource definition:
 
DLGTEMPLATE IDD_CUSTOM_TEST
BEGIN
    DIALOG "", IDD_CUSTOM_TEST, 1, 1, 126, 130, FS_DLGBORDER, 0
    BEGIN
        CONTROL "This is Text", IDD_TITLE,
                 37, 107, 56, 12,
                 WC_STATIC,
                 SS_TEXT | DT_CENTER | DT_TOP | DT_WORDBREAK
                 | WS_VISIBLE
        CONTROL "Custom Control", IDD_CUSTOM,
                 33, 68, 64, 13,
                "MyControlClass",
                WS_VISIBLE
        CONTROL "Okay", DID_OK,
                57, 10, 24, 14,
                WC_BUTTON,
                BS_PUSHBUTTON | BS_DEFAULT | WS_TABSTOP | WS_VISIBLE
    END
END
 
 
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