[Fatal]

I found it last night indirectly over the "PanelViewer" I downloaded here.

So here is what I worked out for minified bank slots (inspired by rushl's "Ultra Mini-packs!"):

<!-- BANKSLOTS -->
<PanelFile ID="ID_UISkin_GamePlay_BankBox">
  <Element ID="GamePlay_BankBox" X="280" Y="750" Width="270" Height="178"> 
    <Element ID="BankDragbar" X="0" Y="0" Width="10" Height="178"> </Element>
    <Element ID="Bank_ItemList" X="10" Y="0" Width="210" Height="178"> </Element>
    <Element ID="BankGraphic" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="Bank_StorageLabel" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="Bank_PurchaseField" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="Bank_AdditionalStorageLabel" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="Bank_OpenSharedAccountBank" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="Bank_AdditionalStorageHelpLabel" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="Bank_AdditionalBagsList" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBackground" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="Bank_Base_Close_Button" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankView_TitleBar" X="0" Y="0" Width="1" Height="1"> </Element>
  </Element>
</PanelFile>


<PanelFile ID="ID_UISkin_BagTemplate">
  <Element ID="BankBagSlot_1" X="280" Y="120" Width="188" Height="105">
    <Element ID="BankBagGraphic" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagBackground" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagDragbar" X="0" Y="0" Width="10" Height="105"> </Element>
    <Element ID="BankBag_Base_Close_Button" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagView_TitleBar" X="0" Y="0" Width="1" Height="1"> </Element>	
    <Element ID="BankBag_ItemList" X="10" Y="0" Width="178" Height="105"> </Element>
  </Element>
  <Element ID="BankBagSlot_2" X="280" Y="225" Width="188" Height="105">
    <Element ID="BankBagGraphic" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagBackground" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagDragbar" X="0" Y="0" Width="10" Height="105"> </Element>
    <Element ID="BankBag_Base_Close_Button" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagView_TitleBar" X="0" Y="0" Width="1" Height="1"> </Element>	
    <Element ID="BankBag_ItemList" X="10" Y="0" Width="178" Height="105"> </Element>
  </Element>
  <Element ID="BankBagSlot_3" X="280" Y="330" Width="188" Height="105">
    <Element ID="BankBagGraphic" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagBackground" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagDragbar" X="0" Y="0" Width="10" Height="105"> </Element>
    <Element ID="BankBag_Base_Close_Button" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagView_TitleBar" X="0" Y="0" Width="1" Height="1"> </Element>	
    <Element ID="BankBag_ItemList" X="10" Y="0" Width="178" Height="105"> </Element>
  </Element>
  <Element ID="BankBagSlot_4" X="280" Y="435" Width="188" Height="105">
    <Element ID="BankBagGraphic" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagBackground" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagDragbar" X="0" Y="0" Width="10" Height="105"> </Element>
    <Element ID="BankBag_Base_Close_Button" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagView_TitleBar" X="0" Y="0" Width="1" Height="1"> </Element>	
    <Element ID="BankBag_ItemList" X="10" Y="0" Width="178" Height="105"> </Element>
  </Element>
  <Element ID="BankBagSlot_5" X="280" Y="540" Width="188" Height="105">
    <Element ID="BankBagGraphic" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagBackground" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagDragbar" X="0" Y="0" Width="10" Height="105"> </Element>
    <Element ID="BankBag_Base_Close_Button" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagView_TitleBar" X="0" Y="0" Width="1" Height="1"> </Element>	
    <Element ID="BankBag_ItemList" X="10" Y="0" Width="178" Height="105"> </Element>
  </Element>
  <Element ID="BankBagSlot_6" X="280" Y="645" Width="188" Height="105">
    <Element ID="BankBagGraphic" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagBackground" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagDragbar" X="0" Y="0" Width="10" Height="105"> </Element>
    <Element ID="BankBag_Base_Close_Button" X="0" Y="0" Width="1" Height="1"> </Element>
    <Element ID="BankBagView_TitleBar" X="0" Y="0" Width="1" Height="1"> </Element>	
    <Element ID="BankBag_ItemList" X="10" Y="0" Width="178" Height="105"> </Element>
  </Element>
  
</PanelFile>

What a hassle to find out! The BankBagSlot_X IDs are *NOT* in the SkinDictionary! Why?
Feel free to reuse it in your skins...

Greets Fatal