MWAPI - DEFBUTTON

Draft MDC Standard

DEFBUTTON specifies the default push button for the window. If the value of DEFBUTTON specifies a gadget which is a child of the window and which has a TYPE attribute value of "BUTTON", the user can "push" the specified button, that is cause it to generate a SELECT event, by pressing a key on the keyboard. The specific key to be pressed is defined by the underlying windowing platform. If focus is not on the button at the time the key is pressed, the SELECT event will be preceded by such UNFOCUS, CHANGE and FOCUS events as would have occurred if the button had been "pushed" using the pointer, during which the request to change focus may be denied.

If an application attempts to assign a value to DEFBUTTON which (a) does not specify a gadget which is a child of the window or (b) does not identify a gadget with a TYPE elattribute value equal to "BUTTON", an error condition occurs with an ecode = "M52" and $EREF containing a value that indicates the ssvn reference for which the invalid DEFBUTTON value was assigned.

The effect is not specified if DEFBUTTON identifies a gadget that has been destroyed after the value identifying it was assigned to DEFBUTTON.

If the window is in build mode the wattribute may be set and referenced but is ignored.