There are a number of significant events that occur during a direct manipulation operation, and which must be communicated to the source and/or target of the operation. These are as follows:
Presentation Manager carries out much of the required notification of drag/drop events using messages, which are passed to the source or target windows as necessary during the drag/drop operation. The required messages are described in the OS/2 2.0 Programming Guide Volume II and their use is discussed in Using Direct Manipulation.
In certain cases, the behavior of a Workplace Shell object participating in a direct manipulation operation varies somewhat from that of a Presentation Manager window. This is due to the fact that the Workplace Shell implements much of the required message handling itself, and directly invokes the appropriate methods in the object. Where the behavior of a Workplace Shell object differs from that of a Presentation Manager window, this is noted in the text.