If you toggle the activation switch to the left of any correction tool then you will have immediate comparison of the before/after state. For example:
… ClearView active:
… ClearView inactive:
Regards, John M
Edit: I think(?) I misunderstood your post, Pierre - - I saw, belatedly, that you were referring to the Active Corrections filter - as per the link you provided.
I don’t use that filter at all - for precisely the reason @Aubrey states: “When one switches off a correction in active correction the correction disappears” … I find it easier/simpler to toggle activation status with Workspace = DxO Standard or Advanced.
Your edit is what I meant. A single-tool “compare” would operate very much like the existing compare button located in the command bar above the image.
Pressing a single tool’s compare button, or other control, would have no effect on the selection and display of active tools (the top right switch in “Filtering and searching corrections”).
A pushbutton would only activate the compare while the button is pressed. Like a physical pushbutton with a spring.
It seems that the behavior you’d like to have is something shared by other users.
It is true that when using the new “Active only” filter available in PL, a user is tempted to compare the ‘with and without’ a correction right there, but without “losing” the temporarily deactivated correction from the list.