For your convenience pools now have a function called purgeLoadedResources exposed to python which will delete all loaded resources that have a ref count of zero. You can use this after closing a map or something alike. It may however impact performance, as the next map may very well reload the same resources. Just be aware of that. :-)

<Window title="Select an option">
	<VBox>
		<ScrollArea size="150,300">
			<ListBox name="optionDrop"/>	
		</ScrollArea>
		<HBox>
			<Button name="okButton" text="OK"/>
			<Button name="cancelButton" text="Cancel"/>
		</HBox>
	</VBox>
</Window>