2. Pointer Motion

When the pointer moves, the initiator sends XmDRAG_MOTION messages to the receiver (which is the top level window the pointer is currently in and which is willing to accept drag messages).

XmDRAG_MOTION

Table: The XmDRAG_MOTION message send by the initiator.

Message User Data	Size	Description
data.b[0]	BYTE	Reason: XmDRAG_MOTION (0x02)
data.b[1]	BYTE	Byte Order: either 'B' (MSB first) or 'l' (LSB first).
data.b[2..3]	CARD16	DnD Flags: 1 + 3
data.b[4..7]	CARD32	Timestamp: set to the timestamp of the corresponding X event triggering this message.
data.b[8..9]	CARD16	Root X: x position of the drag-over icon relative to the root window.
data.b[10..11]	CARD16	Root Y: y position relative to the root window.

Whenever the initiator sends a XmDRAG_MOTION message, the receiver responds with one out of three different messages, depending on whether the pointer entered or left a valid drop site (XmDROP_SITE_ENTER, XmDROP_SITE_LEAVE), or just moved around (XmDRAG_MOTION).

XmDROP_SITE_ENTER

Table: The XmDROP_SITE_ENTER message replied by the receiver.

Message User Data	Size	Description
data.b[0]	BYTE	Reason: XmDROP_SITE_ENTER (0x83)
data.b[1]	BYTE	Byte Order: either 'B' (MSB first) or 'l' (LSB first).
data.b[2..3]	CARD16	DnD Flags: 1 + 2 + 3
data.b[4..7]	CARD32	Timestamp: set to the timestamp of the corresponding X event triggering this message.
data.b[8..9]	CARD16	Root X: better x position (hint for the initiator) of the drag-over icon relative to the root window.
data.b[10..11]	CARD16	Root Y: better y position relative to the root window.

XmDROP_SITE_LEAVE

Table: The XmDROP_SITE_LEAVE message replied by the receiver.

Message User Data	Size	Description
data.b[0]	BYTE	Reason: XmDROP_SITE_LEAVE (0x84)
data.b[1]	BYTE	Byte Order: either 'B' (MSB first) or 'l' (LSB first).
data.b[2..3]	CARD16	(DnD Flags: unused)
data.b[4..7]	CARD32	Timestamp: set to the timestamp of the corresponding X event triggering this message.

XmDRAG_MOTION

Table: The XmDRAG_MOTION message echoed by the receiver.

Message User Data	Size	Description
data.b[0]	BYTE	Reason: XmDRAG_MOTION (0x82)
data.b[1]	BYTE	Byte Order: either 'B' (MSB first) or 'l' (LSB first).
data.b[2..3]	CARD16	DnD Flags: 1 + 2 + 3
data.b[4..7]	CARD32	Timestamp: set to the timestamp of the corresponding X event triggering this message.
data.b[8..9]	CARD16	Root X: better x position (hint for the initiator) of the drag-over icon relative to the root window.
data.b[10..11]	CARD16	Root Y: better y position relative to the root window.