Runs a filter against all plugins in the registry and returns a List with the results.
If the first flag is set, only the first match is returned (as a list with a single object). Every plugin is reffed; use list_free after use, which will unref again.
| this |
registry to query |
| filter |
the filter to use |
| first |
only return first match |
| user_data |
user data passed to the filter function |