I would use a 3 button button to do this. Where a left click on the button would execute the filter and a right click would clear it with a command like:
Select SHOWHIDDEN NOPATTERN
The downside is the button wouldn't display its current state but it would allow you to select or reset the selection with one 3 button button.
Thank you. Isn't there any command to assign a new icon to the button? But that would also make things more complicated, when the button then does not always reflect the real filtering, so the button would need to check also the actual filtering state in the Lister ...
The best solution would be something hardcoded in DOpus for these little but very common problems. For example, turning a CUSTOM filter on and off is something which everyone needs. When it is hardcoded it could also check the actual filter state in the Lister.