I'd like to be able to choose an object, and then select all other objects with similar layer/stroke/fill/style. I can do it by layer, but not style properties.
Selecting by fill and stroke would also take into account style overrides.
You can actually do what you want. After selecting the object, you see it's style in the style editor. If you click the small "check mark" icon in the style preview, that selects all other objects which use that style.
