Volume 6A: Motif Programming Manual

XmN-width, and XmN-depth for specifying those attributes of the image, as well as XmN-hotX and XmN-hotY

for indicating the x,y coordinate of the hotspot for the icon. The XmN-attachment, XmN-offsetX, and

XmN-offsetY resources specify how the icon is attached to the other parts of a drag icon.

There are a number of ways in which you can customize the drag icons that are used for drag and drop. You can

specify default icons for all drag and drop transfers that start from your application by setting various resources of the

Screen object. When you change the default drag icons for the Screen, the toolkit handles the drag−over effects using

the icons, as we discuss in Section #smodicon. An application can also specify custom drag icons for a particular drag

and drop transfer by setting resources on its DragContext object. In this case, the application has to manage the

drag−over visuals using the different DragContext callback routines.

19.2.4 Protocols

For drag and drop to work, the initiating and receiving applications must be able to talk to each other. The Motif

toolkit supports two different mechanisms by which clients can communicate with each other during drag and drop.

The main information that needs to be -passed back and forth during a drag concerns the location of the drag icon

relative to drop sites in the receiving application. The dynamic drag protocol requires messaging between the two

applications, while the preregister drag protocol does not. During the drop, the Xt selection ...