trigger cache flush on settings change

After checking more i see there is a general limitation of the filter caching.

Instead of implementing extended cache_clear_all for each filter, this would be a task that need to be flushed by the filter system itself. All settings changes on a filter are subject to change cached filter results.
This might hit cache_filter, _page, _block, panels, views, ... everything that applies filters and further cache the results.

Related functions
http://api.drupal.org/api/function/cache_clear_all/6
http://api.drupal.org/api/function/filter_cron/6
Some filter_cache is getting cleared here:
http://api.drupal.org/api/function/filter_admin_configure_submit/6
But we still encountered situations where obsolete filter information showed up.

Remember to always flush your caches manually (e.g. by devel) after filter changes.

Switching back to fixed after updates to the cvs.

We needed to implement to flush the filter cache on the global settings page. Changing the configuration there leads to change in processing the filters.

It would be best that the filter system provides some hook to trigger (or even better, an api to flush a filter - triggering the hook) in case of filter changes to flush everything related.