AIX Version 4.3 Differences Guide

• Secondary transfer, also referred to as quick-copy, where the user first selects
a destination and then uses Alt-BTransfer to select data that is moved to the
destination by releasing the pointer button.
In each case, a data transfer can be characterized by the fact that:
• Some data is owned by an application, called the source.
• Another application, called the destination, wants to acquire the data. To
acquire the data, the destination usually sends a request to the owner. The
destination is also called the requestor.
Each particular transfer mechanism in Motif requires a new programming effort to
accommodate, and thus, there is a burden on the programmer if all modes are to
be supported, as recommended by the Motif Style Guide.
In Motif 2.1, OSF has implemented a new mechanism to unify access to the
different mechanisms. Moreover, this mechanism allows the application
programmer the ability to extend the function of toolkit-supplied widgets in the
area of data interchange.
The model is very simple:
• On every widget that can act as source emit data, a convertCallback is
available.
• On every widget that can act as a destination (receive data), a
selectionCallback is available.
The convert callback is called each time the user has requested data through any
mechanism. The programmer only needs to provide a buffer containing the data
and the name of the data type (an atom). Motif automatically transfers the data
and frees the memory after the data has been received. Similarly, the selection
callback tells the programmer that data has arrived.
8.3.3.3 Menu System Improvements
Motif pop-up menus were never simple to program with Motif 1.2. When a pop-up
menu was created, it did not pop-up automatically on the screen when a button
was pressed, some programming was required to make it pop-up. It had the
sense of a task left incomplete, particularly since the code would pop-up a menu
when invoked from the Menu key of the keyboard.
In Motif 2.1, the following was implemented:
• Programmers can freely install pop-up menus on arbitrary widgets in the tree.
For each menu, it is only necessary to specify whether the menu is only valid
for the widget it is installed upon or for children of that widget as well.
• The menu system automatically pops-up the appropriate pop-up menu when
the user of the application presses the appropriate button within the
application.
For the most simple specification of an automatic pop-up, nothing else needs to
be done by the application programmer other than creating the pop-up menu
associated with its manager.
220 AIX Version 4.3 Differences Guide