In our app there are several rather long lists that require vertical scrolling, which is no problem with the default behaviour of an Ext.List component. But since the design the app has a black background the visibility of the default scroller isn't that great.
When inspecting the scroller I saw a class of .x-scrollbar-dark applied to it. Since there is already a class .x-scrollbar-light in the standard sencha css file, one would assume that it should be possible to set something like
ui: 'light'
on the scroller. But I can't find out how...
The API reference doesn't mention the ui property for Ext.util.Scroller. And even if it did: how can you apply it in a list context? The reference for the scroll property of Ext.List says that it accepts a scroller configuration. So I tried something like

scroll: { direction: 'vertical', momentum: false }
But this doesn't seem to have any effect. Am I missing something?
Any help greatly appreciated!