If the currently (globally) active tag filters out all the resources, then the selectors may fail to activate a resource from the user's preset/style and end up returning a null pointer.
This patch just moves the concept of a "hidden" selection from KisResourceItemChooser to KisPatternChooser.
Steps to reproduce:
- In the global pattern chooser create a new tag, don't add any patterns to that, activate the tag
- See that the pattern selector doesn't have a any resources in it
- Open the Layer Styles dialog. Click on the bevel style. See the crash.