Tried hard to grasp the task myself but have tho give up...
Just take the classic example of Event ContentType turned into a widget and set with custom filters on some Aside Zone here http://orchardproject.net/docs/Creating-lists.ashx.
I need to implement very similar to this one but except the custom filtering I need a filter by current page slug.
That is say a specific Event should appear on the aside zone related to the curent page slug.
I really do not want to create a layer per a page and put a new widget with an appropriate custom filter value.
Rather I'd like to make some sort of filtering just for this kind of a widget according to the ContentType filed say RalatedSlug and the current page slug.
Now simply cannot grasp where and how realize this filter.
Please any hint will be appreciated.