Custom Compare() method causes problems...

Seems to work fine here :

Your code with some test stuff added...

Type TElement
	Global glElements:TList

	Field piZ% = 0			'used for layering the sprites (higher Z-values are on top of lower Z-values)

	Method New() 
		If Not glElements Then glElements = CreateList() 
		glElements.AddLast(Self) 
	End Method
	
	Method Kill() 
'none of these functions work because they all use Compare() to find the proper link :(
'		RemoveLink(ListFindLink(glElements, Self)) 
'		ListRemove(glElements, Self)
		glElements.Remove(Self) 
	End Method
		
   Function UpdateAll() 
      For Local e:TElement = EachIn glElements
'         e.update() 
      Next
   End Function
	
'	You must actively call this function in order to get all sprites sorted by Z-value (performance issue)
'	optional argment 'bAscending' can be used to sort the sprites reversed (highest Z-value first)  
	Function SortZ(bAscending% = True) 
		glElements.Sort(bAscending) 
	End Function
		
'	This method is used for sorting the glSprites list in Z-order (ascending)
	Method Compare%(OtherObj:Object)
		Local e:TElement = TElement(OtherObj) 
		If Not e Return Null
		Return piZ - e.piZ
	End Method


'	Abstract Methods
	'Method Update() Abstract
	'Method Draw() Abstract

'	----------------
End Type

Local e:TElement = New TElement
e.piZ = 3

e = New TElement
e.piZ = 1


e = New TElement
e.piZ = 5

DebugLog "Ascending..."
TElement.SortZ()

For e = EachIn TElement.glElements
	DebugLog e.piZ
Next

DebugLog "Descending..."
TElement.SortZ(False)

For e = EachIn TElement.glElements
	DebugLog e.piZ
Next