Puzzled about what is going on internally when a category value is changed and changed data is written to XMP data.

[mkc73]

I think you're right in the sense that if there is no category filter selection the ALT-click behaviour is not well-defined. For instance, if I select a folder and then go to the catalog filter and ALT-click on a category I get no results. ALL does not affect the filter selection but then neither does what is currently displayed in the browser- for instance selecting a folder then going to catalog filter with global match selected the current folder display has no affect on the filter results.

[mkc73]

It might be more transparent if, when using the catalog filter, the images currently displayed in the browser always matched the current selection and do away with the global match and current folder match options. Then when a folder is selected and then the catalog filter is selected the current folder contents are displayed and selected (ie current folder match). And if ALL is selected all images are displayed and selected (ie global match).

[user0]

imo it should work like this:

'All' is not the same as no selection, it's all files in the catalog.

but resetting/clearing filters should revel all files, limited only by Match option:
- global - show all files in catalog
- current folder (+subfolders) - show all cataloged files from current folder (+subfolders)

Browser - Catalog filter - add Unset filters and rework Special items

[xnview]

Just to be clear : in the case where the category change only affects one file of the 10000 selected, all 10000 image files are updated ?

Currently yes, but shouldnt

Thanks to your detailed description I can reproduce the problem.