Here're my suggestions for improving thumb cache maintainability:
1. The easy way: make the cache list sortable on columns. With this it'll be much easier to locate and multi-select unwanted caches (e.g. cached temporary download folders) and remove with single click.
2. The once-and-for-all solution: Use include/exclude lists to allow user difine which folders (and their subfolders) should be cached, which should not. No unwanted caches will be generated in the first place. So it will be all up to users to setup, not for Pierre to worry about any more.
