DCollapsibleCategory being weird

[[CLRP]extra]

EDIT: Fixed again by the amazing Boxama. Locking.

EDIT: The main derma panel these open on is a Derma Panel connected to a DProperty Sheet. No idea if that is the problem.

For some reason this code does not work as it should:

TheListPanel = vgui.Create( "DPanelList", SheetItemTwo )
TheListPanel:SetTall( SheetItemTwo:GetTall() *.975 )
TheListPanel:SetWide( SheetItemTwo:GetWide() *.975 )
TheListPanel:Center()
TheListPanel:EnableVerticalScrollbar( true )
TheListPanel:EnableHorizontal( true ) 

Category = vgui.Create( "DCollapsibleCategory" )
Category:SetSize( TheListPanel:GetWide() *.965, TheListPanel:GetTall() *.925  )
Category:SetPos(0,TheListPanel:GetTall() *.25)
Category:SetLabel( "s" )


CategoryList = vgui.Create( "DPanelList" )
CategoryList:SetTall( TheListPanel:GetTall() *.95 )
CategoryList:SetWide( TheListPanel:GetWide() *.975 )
CategoryList:EnableVerticalScrollbar( true )
CategoryList:SetSpacing(5)
CategoryList:EnableHorizontal( true )


for k, v in pairs(CWRP_Craftables) do
	
	local ItemList = vgui.Create("DPanel")
			ItemList:SetTall( TheListPanel:GetTall() *.6 )
			ItemList:SetWide( TheListPanel:GetWide() )
			ItemList:SetPos( 0, 0 )
			ItemList.Paint = function()
				draw.RoundedBox(8,0,2,ItemList:GetWide(),ItemList:GetTall(),Color( 100, 101, 100, 255 ))
			end
				
			local ItemBackground = vgui.Create( "DPanel", ItemList )
			ItemBackground:SetPos( 0, 2 )
			ItemBackground:SetSize( ItemList:GetWide(), ItemList:GetTall() )
			ItemBackground.Paint = function()
			    draw.RoundedBox(8,0,2,ItemBackground:GetWide(),ItemBackground:GetTall(),Color( 80, 81, 80, 255 ))
			end		
            
CategoryList:AddItem(ItemList)
end
Category:SetContents(CategoryList)
TheListPanel:AddItem(Category)

Opening the panel results in this:

[IMG]http://s11.postimg.org/f46q1dgbn/image.png[/IMG]

Collapsing the category and reopening it results in this:

[IMG]http://s1.postimg.org/d5cc2xgnj/image.png[/IMG]

Collapsing it and reopening again results in this:

[IMG]http://s9.postimg.org/ikjc2d7hr/image.png[/IMG]

This is very strange, am I doing this right?

[[CLRP]extra]

Anyone?