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**Isomorphic** · 17 Nov 2011, 12:15

You've wiped out SmartClient's rendered DOM via direct DOM manipulation. We know your team is using GWT with SmartClient without SmartGWT, but we see people reporting this error with SmartGWT every so often, and it's in the SmartGWT FAQ. A typical cause is doing something like (GWT)Panel.clear() where there are SmartClient components inside the Panel.

**acarur01** · 17 Nov 2011, 12:19

We only use GWT for client/server communication - We don't actually use GWT for UI stuff.

**Isomorphic** · 17 Nov 2011, 12:24

It's either your GWT usage clearing out the DOM, or some other direct-to-DOM coding you (or a third-party library) is doing. We'd look very hard at GWT first. Using GWT just for client-server comm does not imply that it leaves the DOM entirely alone (history management, script tag insertion, etc).

**acarur01** · 8 Dec 2011, 07:35

Was able to reproduce as a standalone - also, I've pinpointed it to markForDestroy() - I've tested with destroy() and it works fine. The problem lies in the group3 section. We have two dynamic forms both having a section item called group3.

Reproduceable in IE and FF. It first fails at "_5=_11.currentStyle"

"Object required ISC_Core.js, line 1930 character 105"

Code:



<HTML><HEAD><TITLE>Mark For Destroy Error</TITLE>
    <SCRIPT>var isomorphicDir = "isomorphic/"</SCRIPT>
    <SCRIPT SRC=isomorphic/system/modules/ISC_Core.js></SCRIPT>
    <SCRIPT SRC=isomorphic/system/modules/ISC_Foundation.js></SCRIPT>
    <SCRIPT SRC=isomorphic/system/modules/ISC_Containers.js></SCRIPT>
    <SCRIPT SRC=isomorphic/system/modules/ISC_Grids.js></SCRIPT>
    <SCRIPT SRC=isomorphic/system/modules/ISC_Forms.js></SCRIPT>
    <SCRIPT SRC=isomorphic/system/modules/ISC_DataBinding.js></SCRIPT>
	<SCRIPT SRC=isomorphic/skins/Enterprise/load_skin.js></SCRIPT>
</HEAD><BODY CLASS="pageBackground">


<SCRIPT>

isc.setAutoDraw(false);

isc.VLayout.create({ID:"testVLayout", width: 300});
isc.TreeGrid.create({
    ID: "employeeTree",
    
    data: isc.Tree.create({
        modelType: "children",
        nameProperty: "Name",
        childrenProperty: "directReports",
        root: {EmployeeId: "1", directReports: [
            {EmployeeId:"4", Name:"Charles Madigen", directReports: [
                {EmployeeId:"188", Name:"Rogine Leger"},
                {EmployeeId:"189", Name:"Gene Porter", directReports: [
                    {EmployeeId:"265", Name:"Olivier Doucet"},
                    {EmployeeId:"264", Name:"Cheryl Pearson"}
                ]}
            ]}
        ]}
    }),

    // customize appearance
    width: 500,
    height: 400,
    nodeIcon:"icons/16/person.png",
    folderIcon:"icons/16/person.png",
    showOpenIcons:false,
    showDropIcons:false,
    closedIconSuffix:"",

recordClick: function(viewer, record, recordNum, field, fieldNum, value, rawValue){
	
	if(this.cwTestGrid!=null)
		this.cwTestGrid.markForDestroy();
		
		if(recordNum == 1){
			this.cwTestGrid = isc.VStack.create({
							ID:"orderHeaderGrid_vCentering",
							name:"orderHeaderGrid_vCentering",
							vPolicy:"fill",hPolicy:"fill",
							height:"100%",width:"100%",members:
							[isc.DynamicForm.create({
							width:960,
							ID:"orderHeaderGrid",
							name:"orderHeaderGrid",
							numCols:4,
							colWidths:["240","240","240","240"],
							titleOrientation:"top",
							fields:
							[{_constructor:"SectionItem",
							isFirstFocusable:false,
							ID:"group3",
							title:"External Interface &nbsp;",
							canCollapse:false,
							defaultValue:"External Interface",
							sectionExpanded:true,
							endRow:true,itemIds:[]}]})]});

		}
		if(recordNum == 2){
			   this.cwTestGrid = isc.VStack.create({
							ID:"siteAddressGrid_vCentering",
							name:"siteAddressGrid_vCentering",
							vPolicy:"fill",hPolicy:"fill",
							height:"100%",width:"100%",members:
							[isc.DynamicForm.create({
							width:960,
							ID:"siteAddressGrid",
							name:"siteAddressGrid",
							numCols:4,
							colWidths:["240","240","240","240"],
							titleOrientation:"top",
							fields:
							[{_constructor:"SectionItem",
							isFirstFocusable:false,
							ID:"group3",
							title:"GAV Location&nbsp;",
							canCollapse:false,
							defaultValue:"GAV Location",
							sectionExpanded:true,
							endRow:true,itemIds:[]}]})]});
		}
		
		if(recordNum == 3){
			this.cwTestGrid = isc.VStack.create({
							ID:"accessGrid_vCentering",
							name:"accessGrid_vCentering",
							vPolicy:"fill",hPolicy:"fill",
							height:"100%",width:"100%",members:
							[isc.DynamicForm.create({
							width:960,
							ID:"accessGrid",
							name:"accessGrid",
							numCols:4,
							colWidths:["240","240","240","240"],
							titleOrientation:"top",
							fields:
							[{_constructor:"HeaderItem",
							isFirstFocusable:false,
							defaultValue:"access"}]})]});
		
		}
		
		
		
	testVLayout.addMember(this.cwTestGrid);
	}
});



isc.HLayout.create({ID:"testHLayout", autoDraw:true,members:[employeeTree, testVLayout]});

</script>
</body></html>

**Isomorphic** · 8 Dec 2011, 16:46

This error is preceded in the logs by a warning about colliding IDs, because what's happening is, the new form is destroying parts of the old form as it's being created, including the generated Section header which is part of a CanvasItem.

You can prevent this, as you've noted, via destroy() instead of markForDestroy(). Generally, use markForDestroy() if you are in the middle of an event handler in the widget you want to destroy, because it's invalid to destroy a widget *during* event handling. If you're done with a widget and you're creating a new set of components that will possibly collide on global IDs, destroy() the old widgets first before creating the new ones.

**acarur01** · 9 Dec 2011, 05:38

But how to do I even detect that they could possibly collide? In our system, this would mean calling destroy() on all the layouts - how do I pinpoint when to call it and when to call markForDestroy?

**Isomorphic** · 9 Dec 2011, 11:24

Remember, we don't have your code in front of us :)

As a general approach, if you've called markForDestroy() on something then presumably your code is assuming that any IDs you used in that widget hierarchy are now free to re-use. So you could make sure anything you've marked for destroy is in fact synchronously destroyed before you show new widgets.

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