[TYPO3-Solr] tx_solr_file - updating files doesn't work

[Alexander Wende]

We use tx_solr (3.0.0-dev), tx_solr_file (1.0.1) and tx_solr_fal(1.0.0-dev) to index files.
File indexing works fine but when files are changed in the filesystem the extension doesn't recognize it.

For me it looks like the extension refreshed the 'changed' field only if the referencing content element is changed. 
Is this a bug, a feature or  just a misconfiguration?

 
As a workarround I could provide a scheduler skript which refreshes the "changed" field