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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-NZ link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>Yes I realize that, but I didn’t know that was possible with TListItems which the VCL manages for you. I need to know what situations will cause that. I really need access to all the items in the listview immediately at any time. The app will not run correctly if something is freeing list items willy nilly.<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>Presumably a RecreateWnd() is being executed on the ListView for some reason other than any code in the software. I’ve checked the VCL source code for TCustomListView and where RecreateWnd is being executed, and it’s only with a change to a handful of Properties which I am not altering in code. So Windows is doing this itself for some reason.<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>I think I will have to subclass the TListView's WindowProc property to look for CM_RECREATEWND and WM_DESTROY messages, and stop all processing until this is finished. Hopefully that will sort it out. What a bloody hassle.<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>Ross.<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> <o:p></o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> delphi-bounces@listserver.123.net.nz [mailto:delphi-bounces@listserver.123.net.nz] <b>On Behalf Of </b>Todd Martin<br><b>Sent:</b> Thursday, 11 April 2013 10:04 a.m.<br><b>To:</b> NZ Borland Developers Group - Delphi List<br><b>Subject:</b> Re: [DUG] TListitems disappearing and reappearing causing access violations<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Hi Ross<br><br>Clearly the problem is NOT that the items are being removed from the list. Rather the items are being freed, (from previous comments) in various places, yet not removed. <br><br>Just because <span style='font-family:"Calibri","sans-serif"'>assigned(PlayView.Items[i]) is true, does not mean that that instance exists. It means that the object pointer is not nil. Do you understand the difference between a nil pointer and a pointer to memory that is no longer in use?<br><br>Todd.<br><br><br><br></span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>I’ve heard today that TeamViewer isn’t in use when the problem occurs. They often use it to resolve the issue after the problem has occurred.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>They tell me they have seen it in mid-song where all the tracks disappear and the app then becomes unresponsive or crashes because of the app still accessing items that don’t exist.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>There are no deletion routines in the program which delete every item from the listview, so that’s not what’s going on. Considering there are around 5000 users who have no problems at all, I don’t think it can be a coding problem. There has been the very rare issue like this reported over the years but this one user is getting it regularly, like every couple of days.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>I thought I was on to something with remote control app but it appears not. </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>Another reported crash a couple of weeks ago was here…</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>i := Item.Index;</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>while (i < PlayView.Items.Count) and (PlayView.Items[i].Caption = EventTimeStr) do</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>…</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>The “while” line crashed with Access Violation in ComCtrls.TListItems.GetItem, and the screen shot again showed no items. This should prove that it cannot be the software removing the items as otherwise Items.Count would be 0.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>Someone else with dual monitors had a crash on the same line about 6 months ago and it has now been modified to validate items[i] is a real item before retrieving the caption. This will stop the error but the software will not function correctly.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>Cheers.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'> </span><o:p></o:p></p><div><div style='border:none;border-top:solid windowtext 1.0pt;padding:3.0pt 0cm 0cm 0cm;border-color:-moz-use-text-color -moz-use-text-color'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> <a href="mailto:delphi-bounces@listserver.123.net.nz">delphi-bounces@listserver.123.net.nz</a> [<a href="mailto:delphi-bounces@listserver.123.net.nz">mailto:delphi-bounces@listserver.123.net.nz</a>] <b>On Behalf Of </b>Ross Levis<br><b>Sent:</b> Wednesday, 10 April 2013 2:38 a.m.<br><b>To:</b> 'NZ Borland Developers Group - Delphi List'<br><b>Subject:</b> Re: [DUG] TListitems disappearing and reappearing causing access violations</span><o:p></o:p></p></div></div><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>I guess I am. It makes the most sense. I’ll have to try a test with TeamViewer to duplicate it.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'> </span><o:p></o:p></p><div style='border:none;border-top:solid windowtext 1.0pt;padding:3.0pt 0cm 0cm 0cm;border-color:rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> <a href="mailto:delphi-bounces@listserver.123.net.nz">delphi-bounces@listserver.123.net.nz</a> [<a href="mailto:delphi-bounces@listserver.123.net.nz">mailto:delphi-bounces@listserver.123.net.nz</a>] <b>On Behalf Of </b>Kyley Harris<br><b>Sent:</b> Wednesday, 10 April 2013 12:48 a.m.<br><b>To:</b> NZ Borland Developers Group - Delphi List<br><b>Subject:</b> Re: [DUG] TListitems disappearing and reappearing causing access violations</span><o:p></o:p></p></div><p class=MsoNormal> <o:p></o:p></p><div><div><p class=MsoNormal style='margin-bottom:12.0pt'>I think the problem is that right now you are running on the Theory that they are being reconstructed as you state, and you have not created a test scenario to validate what you are saying. <o:p></o:p></p></div><p class=MsoNormal>it could just be a coding error, and the delete event will tell you when a list item is being destroyed. That list item will not be destroyed if the window handle is reconstructed. Not in the source code I can see.,<o:p></o:p></p></div><div><p class=MsoNormal style='margin-bottom:12.0pt'> <o:p></o:p></p><div><p class=MsoNormal>On Wed, Apr 10, 2013 at 12:41 AM, Ross Levis <<a href="mailto:ross@stationplaylist.com" target="_blank">ross@stationplaylist.com</a>> wrote:<o:p></o:p></p><div><div><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>Actually that doesn’t help so much. I really need to know when Windows is deleting the items. My app also deletes items. I guess I could remove the OnDeletion event property before coding a delete and reinstate if afterwards. A little messy.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>I really need to associate the individual deleted items with the identical new items that will be created just afterwards. Ideally I would want my app to stop processing all timers and functions while the deletions and recreations are done.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>Getting too complicated.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><div style='border:none;border-top:solid windowtext 1.0pt;padding:3.0pt 0cm 0cm 0cm;border-color:-moz-use-text-color -moz-use-text-color'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> <a href="mailto:delphi-bounces@listserver.123.net.nz" target="_blank">delphi-bounces@listserver.123.net.nz</a> [mailto:<a href="mailto:delphi-bounces@listserver.123.net.nz" target="_blank">delphi-bounces@listserver.123.net.nz</a>] <b>On Behalf Of </b>Kyley Harris</span><o:p></o:p></p><div><p class=MsoNormal><br><b>Sent:</b> Wednesday, 10 April 2013 12:06 a.m.<o:p></o:p></p></div><div><div><p class=MsoNormal><b>To:</b> NZ Borland Developers Group - Delphi List<br><b>Subject:</b> Re: [DUG] TListitems disappearing and reappearing causing access violations<o:p></o:p></p></div></div></div><div><div><p class=MsoNormal> <o:p></o:p></p><div><p class=MsoNormal>the listview has an Ondeletion event. when that fires, you should check the index, and remove any listitem references from your tlist. <br><br>The issue seems to be that you are mixing view objects with data objects. the system might go more smoothly if you were containing your data objects disctinct from your view (tlistview) and synchronizing the view to the source. <o:p></o:p></p></div><div><p class=MsoNormal style='margin-bottom:12.0pt'> <o:p></o:p></p><div><p class=MsoNormal>On Tue, Apr 9, 2013 at 11:58 PM, Ross Levis <<a href="mailto:ross@stationplaylist.com" target="_blank">ross@stationplaylist.com</a>> wrote:<o:p></o:p></p><div><div><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>It isn’t a user initiated procedure. It’s a broadcast media player in automation mode and each track is a listitem. Items can be dropped off the top and more added to the bottom as it plays automated.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>There is a TTimer which accesses all the items in the list once a second to provide totals and such. So the items are accessed very regularly.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>Some of the list items are timed events which need to occur at a specific time. These item pointers are stored in a TList so the software can easily access the next one without having to look for it in the list.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>This user has had issues with the code that accesses this TList of TListitem pointers, so that sounds like the pointers to the listitems have been changed.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>Ideally the listitems shouldn’t be accessed directly and a separate data store should be used that is linked to each item via the Data property. A bit too late for that now though.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>So it sounds like I need to find the Windows message that is being sent to the app to recreate windows and do some housekeeping.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>Any ideas what that might be?</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><div style='border:none;border-top:solid windowtext 1.0pt;padding:3.0pt 0cm 0cm 0cm;border-color:-moz-use-text-color -moz-use-text-color'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> <a href="mailto:delphi-bounces@listserver.123.net.nz" target="_blank">delphi-bounces@listserver.123.net.nz</a> [mailto:<a href="mailto:delphi-bounces@listserver.123.net.nz" target="_blank">delphi-bounces@listserver.123.net.nz</a>] <b>On Behalf Of </b>Kyley Harris<br><b>Sent:</b> Tuesday, 9 April 2013 11:35 p.m.</span><o:p></o:p></p><div><div><p class=MsoNormal><br><b>To:</b> NZ Borland Developers Group - Delphi List<br><b>Subject:</b> Re: [DUG] TListitems disappearing and reappearing causing access violations<o:p></o:p></p></div></div></div><div><div><p class=MsoNormal> <o:p></o:p></p><div><div><p class=MsoNormal style='margin-bottom:12.0pt'>If that was the case.. then its unlikely to happen midstream during a very small short procedure call. Especially if that procedure call is a user initiated one. <o:p></o:p></p></div><p class=MsoNormal>if that is the case.. its extremely simple to test this with remote desktop and some logging of the construction/destruction of the list items.<o:p></o:p></p></div><div><p class=MsoNormal style='margin-bottom:12.0pt'> <o:p></o:p></p><div><p class=MsoNormal>On Tue, Apr 9, 2013 at 11:29 PM, Ross Levis <<a href="mailto:ross@stationplaylist.com" target="_blank">ross@stationplaylist.com</a>> wrote:<o:p></o:p></p><div><div><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>I’ve had someone suggest this elsewhere…</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><i><span style='font-family:"Calibri","sans-serif"'>The user connects a monitor to a laptop, or connects remotely via <br>terminal services.<br>Basically, anything that changes the display resolution has that kind of <br>consequences.</span></i><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>I have seen a TeamViewer in one of the many screen shots. So I guess Windows is recreating the windows and allocating new handles to the list items as I thought. I’ll check with them if the crashes coincide with use of TeamViewer.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>Ross.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><div><div style='border:none;border-top:solid windowtext 1.0pt;padding:3.0pt 0cm 0cm 0cm;border-color:rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Ross Levis [mailto:<a href="mailto:ross@stationplaylist.com" target="_blank">ross@stationplaylist.com</a>] <br><b>Sent:</b> Tuesday, 9 April 2013 11:17 p.m.<br><b>To:</b> 'NZ Borland Developers Group - Delphi List'<br><b>Subject:</b> RE: [DUG] TListitems disappearing and reappearing causing access violations</span><o:p></o:p></p></div></div><div><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>The list is populated by the software. It’s still in Delphi 7.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>No threads are deleting any items. Only the main thread adds and removes items.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>There is no one procedure this has occurred in. It can work for 2 days and suddenly this happens in a random procedure that accesses a list item.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>In this particular case, it is in a procedure where one specific listitem is sent as a parameter.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>Here are some of the relevant lines of code in the procedure being executed.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> if Item <> nil then</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> begin</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> if Item.Selected then UpdateButtons;</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> …</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> Item.ImageIndex := 8;</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> end;</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>There are no deletions in the procedure.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>The Item.Selected test works fine but Item.ImageIndex := 8 crashes at TListItem.SetImage with an access violation.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>The item existed and then no items exist based on the screen shot.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>I’ve been having to put validations all over the place like this…</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>if ListView.Items.IndexOf(Item) >= 0 then Listitem.ImageIndex := 8.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>This user has had a crash where it does this validation up the procedure somewhere which validated, but further down it will be accessing Item.Index and this crashes.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>It’s a nightmare. I’m wondering if it could be corrupt RAM in the PC or something.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>Cheers,</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>Ross.</span><o:p></o:p></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><div style='border:none;border-top:solid windowtext 1.0pt;padding:3.0pt 0cm 0cm 0cm;border-color:rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> <a href="mailto:delphi-bounces@listserver.123.net.nz" target="_blank">delphi-bounces@listserver.123.net.nz</a> [<a href="mailto:delphi-bounces@listserver.123.net.nz" target="_blank">mailto:delphi-bounces@listserver.123.net.nz</a>] <b>On Behalf Of </b>Kyley Harris<br><b>Sent:</b> Tuesday, 9 April 2013 10:33 p.m.<br><b>To:</b> NZ Borland Developers Group - Delphi List<br><b>Subject:</b> Re: [DUG] TListitems disappearing and reappearing causing access violations</span><o:p></o:p></p></div><p class=MsoNormal> <o:p></o:p></p></div><div><div><div><div><p class=MsoNormal style='margin-bottom:12.0pt'>without seeing the 10lines above, and whats inbetween (if you were being literal) its very hard to say. <o:p></o:p></p></div><div><div><p class=MsoNormal style='margin-bottom:12.0pt'>The only time I've ever had something dissapear from a list is when I deleted it though a callback, method, thread etc.. or freeing something. <o:p></o:p></p></div></div></div><div><div><p class=MsoNormal style='margin-bottom:12.0pt'>what version of delphi is the code now? How does the list get populated or edited by the application.. <o:p></o:p></p></div></div></div><div><div><p class=MsoNormal>I'd start by looking at how many locations of code insert or delete the list items, and verify none are being called while your procedure is executing its for-loop, (assuming the access violation is an index based one because of the list count change)<o:p></o:p></p><div><p class=MsoNormal style='margin-bottom:12.0pt'> <o:p></o:p></p></div></div></div></div><div><div><div><p class=MsoNormal style='margin-bottom:12.0pt'> <o:p></o:p></p><div><p class=MsoNormal>On Tue, Apr 9, 2013 at 10:21 PM, Ross Levis <<a href="mailto:ross@stationplaylist.com" target="_blank">ross@stationplaylist.com</a>> wrote:<o:p></o:p></p><div><div><p class=MsoNormal>Wondering if anyone has any ideas.<o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal>I've had this problem a long time from when I started writing an app about 7 or 8 years ago, but it happens so rarely it's not usually an issue. But one user in particularly is regularly sending me MadExcept reports which either have access violation errors or "the application appears to be frozen". In all cases it's during an access of a TListItem which was perfectly valid 10 lines of code up a procedure but suddenly doesn't exist.<o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal>The screenshot created at the same time shows the ListView has no visible items, but I know for a fact there are 30 or more items in the list. I believe sometimes the items visually disappear and reappear shortly afterwards, like a Desktop refresh.<o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal>I think I've heard something about Windows recreating the window handles or some such thing. I don't understand why it would do so. There are no changes to the listview that would require re-creating the window.<o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal>Any ideas?<o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p></div></div><p class=MsoNormal><br>_______________________________________________<br>NZ Borland Developers Group - Delphi mailing list<br>Post: <a href="mailto:delphi@listserver.123.net.nz" target="_blank">delphi@listserver.123.net.nz</a><br>Admin: <a href="http://delphi.org.nz/mailman/listinfo/delphi" target="_blank">http://delphi.org.nz/mailman/listinfo/delphi</a><br>Unsubscribe: send an email to <a href="mailto:delphi-request@listserver.123.net.nz" target="_blank">delphi-request@listserver.123.net.nz</a> with Subject: unsubscribe<o:p></o:p></p></div><p class=MsoNormal><br><br clear=all><br>-- <br>Kyley Harris<br>Harris Software<br>+64-21-671-821 <o:p></o:p></p></div></div></div></div></div><p class=MsoNormal><br>_______________________________________________<br>NZ Borland Developers Group - Delphi mailing list<br>Post: <a href="mailto:delphi@listserver.123.net.nz" target="_blank">delphi@listserver.123.net.nz</a><br>Admin: <a href="http://delphi.org.nz/mailman/listinfo/delphi" target="_blank">http://delphi.org.nz/mailman/listinfo/delphi</a><br>Unsubscribe: send an email to <a href="mailto:delphi-request@listserver.123.net.nz" target="_blank">delphi-request@listserver.123.net.nz</a> with Subject: unsubscribe<o:p></o:p></p></div><p class=MsoNormal><br><br clear=all><br>-- <br>Kyley Harris<br>Harris Software<br>+64-21-671-821 <o:p></o:p></p></div></div></div></div></div><p class=MsoNormal><br>_______________________________________________<br>NZ Borland Developers Group - Delphi mailing list<br>Post: <a href="mailto:delphi@listserver.123.net.nz" target="_blank">delphi@listserver.123.net.nz</a><br>Admin: <a href="http://delphi.org.nz/mailman/listinfo/delphi" target="_blank">http://delphi.org.nz/mailman/listinfo/delphi</a><br>Unsubscribe: send an email to <a href="mailto:delphi-request@listserver.123.net.nz" target="_blank">delphi-request@listserver.123.net.nz</a> with Subject: unsubscribe<o:p></o:p></p></div><p class=MsoNormal><br><br clear=all><br>-- <br>Kyley Harris<br>Harris Software<br>+64-21-671-821 <o:p></o:p></p></div></div></div></div></div><p class=MsoNormal><br>_______________________________________________<br>NZ Borland Developers Group - Delphi mailing list<br>Post: <a href="mailto:delphi@listserver.123.net.nz">delphi@listserver.123.net.nz</a><br>Admin: <a href="http://delphi.org.nz/mailman/listinfo/delphi" target="_blank">http://delphi.org.nz/mailman/listinfo/delphi</a><br>Unsubscribe: send an email to <a href="mailto:delphi-request@listserver.123.net.nz">delphi-request@listserver.123.net.nz</a> with Subject: unsubscribe<o:p></o:p></p></div><p class=MsoNormal><br><br clear=all><br>-- <br>Kyley Harris<br>Harris Software<br>+64-21-671-821 <o:p></o:p></p></div><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>_______________________________________________<o:p></o:p></pre><pre>NZ Borland Developers Group - Delphi mailing list<o:p></o:p></pre><pre>Post: <a href="mailto:delphi@listserver.123.net.nz">delphi@listserver.123.net.nz</a><o:p></o:p></pre><pre>Admin: <a href="http://delphi.org.nz/mailman/listinfo/delphi">http://delphi.org.nz/mailman/listinfo/delphi</a><o:p></o:p></pre><pre>Unsubscribe: send an email to <a href="mailto:delphi-request@listserver.123.net.nz">delphi-request@listserver.123.net.nz</a> with Subject: unsubscribe<o:p></o:p></pre><p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p><div><p class=MsoNormal>-- <br><i>Fortune</i> favours the <b>brave</b><o:p></o:p></p></div></div></body></html>