thank you for sharing this subject.
It is said that
Returns: {Boolean} If hook returns
false
value then filtering won’t be applied on the UI side (server-side filtering).
src Hooks API reference - JavaScript Data Grid | Handsontable
But it doesn’t seem to be true here Handsontable example - JSFiddle - Code Playground where the filter is applied for each column.
However, it works like this Handsontable example - JSFiddle - Code Playground
Nevetheless, you are right. I do not see why the dropdown menu arrow changed the color as the filtering is blocked. We also see that the option removed from the filter by value
are still gone even if they are stll visible.
I reported this case here beforeFilter doesn't provide a full filter block · Issue #6558 · handsontable/handsontable · GitHub and will keep you updated with the changes.