s:List change event is not being triggered

[pashminakazi]

Project Details are :
https://paste.apache.org/cpo8y
Test case is available on VDI.
Go to Import from Select in Menu
Go to Import -> Import Chargesfrom Setups in Menu
File : com/dbz/modules/IMP/dbzImportChargesSetup.mxml

Click on this button :
https://user-images.githubusercontent.com/42200979/77047368-6ec4b080-69e6-11ea-9fda-6f316d7c0ddc.png
New window will be opened which is : com/dbz/modules/IMP/dbzimportChargerFormulaPopup

In Flex
when we double click any element from s:List with ID lstSysVariable named system Columns a change event is triggered fn_addSysColumns

private function fn_addSysColumns(e:Event):void {
				selectedListItem = List(e.currentTarget).selectedItem;
				impchg_Formula_Disp.text = impchg_Formula_Disp.text + " " + selectedListItem.label;
				impchg_Formula.text = impchg_Formula.text + " " + selectedListItem.id;
				
			}

and that element will be added in Formula Editor which is mx:TextArea
<mx:TextArea id="impchg_Formula_Disp" maxChars="400" width="593" tabIndex="1" x="1" y="2" height="146" valueCommit="bValidate=false;"/>

In Royale
when i double click on any element from system column nothing is added in Formula Editor TextArea because change event is not being triggered

[aharui]

On the first click of the double-click, does the list selection change? If you make a simple test case with s:List, does the list selection change?

[pashminakazi]

@aharui Thanks now change event is being triggered..
but there's an exception in function which is called on change event.

Change function :

private function fn_addSysColumns(e:Event):void {
				selectedListItem = List(e.currentTarget).selectedItem;
				impchg_Formula_Disp.text = impchg_Formula_Disp.text + " " + selectedListItem.label;
				impchg_Formula.text = impchg_Formula.text + " " + selectedListItem.id;
				
			}

selectedListItem is null that's why selectedListItem .label is null
why selectedListItem is setted null?
selectedListItem is object variable

[pashminakazi]

@aharui Thank u so much.
On a single click value is added in formula editor 2 times