XGDragView bug

[Enrico Sersale]

The recent changes in XGDragView cause some crashes in GWorkspace.

This is completly reproducable:

1) select a file.

2) drag its icon a bit around and then back to its place.

3) select an other file to change the contents of the pasteboard.

4) try to drag again.

5) the app crashes.

#0  objc_msg_lookup (receiver=0x85caf80, op=0x402cf040)
    at ../../../gcc-3.0.1/libobjc/objc/sarray.h:230
#1  0x401d5a3f in -[NSWindow sendEvent:] (self=0x868e610, _cmd=0x407b1fb8,
    theEvent=0x858f8d8) at NSWindow.m:2904
#2  0x4077a256 in -[XGDragView
_sendLocalEvent:action:position:timestamp:toWindow:] (self=0x84a6538,
_cmd=0x407b22e0, subtype=GSAppKitDraggingEnter,
    action=NSDragOperationAll, eventLocation={x = 357, y = 340}, time=0,
    dWindow=0x868e610) at SharedX/XGDragView.m:305
#3  0x4077c20d in -[XGDragView _updateAndMoveImageToCorrectPosition] (
    self=0x84a6538, _cmd=0x407b2180) at SharedX/XGDragView.m:935
#4  0x4077b241 in -[XGDragView _handleDrag:] (self=0x84a6538,
_cmd=0x407b1f90,
    theEvent=0x8494350) at SharedX/XGDragView.m:641
#5  0x4077a06d in -[XGDragView
dragImage:at:offset:event:pasteboard:source:slideBack:] (self=0x84a6538,
_cmd=0x402cf278, anImage=0x85fa918, screenLocation={
      x = 499, y = 614}, initialOffset={width = 0, height = 0},
    event=0x8494350, pboard=0x83a4d08, sourceObject=0x853cea0,
    slideFlag=0 '\000') at SharedX/XGDragView.m:276
#6  0x401d6988 in -[NSWindow
dragImage:at:offset:event:pasteboard:source:slideBack:] (self=0x868e610,
_cmd=0x402cbe88, anImage=0x85fa918, baseLocation={
      x = 357, y = 338}, initialOffset={width = 0, height = 0},
    event=0x8494350, pboard=0x83a4d08, sourceObject=0x853cea0,
    slideFlag=0 '\000') at NSWindow.m:3146
#7  0x401c7821 in -[NSView
dragImage:at:offset:event:pasteboard:source:slideBack:] (self=0x853cea0,
_cmd=0x4098c230, anImage=0x85fa918, viewLocation={x = 59,
      y = 19}, initialOffset={width = 0, height = 0}, event=0x8494350,
    pboard=0x83a4d08, sourceObject=0x853cea0, slideFlag=0 '\000')
    at NSView.m:2530
#8  0x40979f11 in -[ColumnIcon(DraggingSource) startExternalDragOnEvent:]
(
    self=0x853cea0, _cmd=0x4098bdb8, event=0x8494350) at ColumnIcon.m:603
#9  0x40977a22 in -[ColumnIcon mouseDown:] (self=0x853cea0,
_cmd=0x402cee10,
    theEvent=0x87250b0) at ColumnIcon.m:396
#10 0x401d4a3c in -[NSWindow sendEvent:] (self=0x868e610, _cmd=0x4027e998,
    theEvent=0x87250b0) at NSWindow.m:2655
#11 0x400bc03c in -[NSApplication sendEvent:] (self=0x813e430,
    _cmd=0x4027e6f0, theEvent=0x87250b0) at NSApplication.m:1320
#12 0x400baadb in -[NSApplication run] (self=0x813e430, _cmd=0x80f2778)
    at NSApplication.m:902
#13 0x804c4e5 in main (argc=1, argv=0xbfffeb54, env=0xbfffeb5c) at
main.m:41
#14 0x40582091 in __libc_start_main (main=0x804c3a0 <main>, argc=1,
    ubp_av=0xbfffeb54, init=0x804c0c8 <_init>, fini=0x80b0280 <_fini>,
    rtld_fini=0x4000e374 <_dl_fini>, stack_end=0xbfffeb4c)
    at ../sysdeps/generic/libc-start.c:129