As we all know, Okular is a great piece of software. One of the feature I most like in Okular is the review tools, a system that allows to make any kind of annotation in the document. When I’ve begun using it, I noticed that after selecting a tool and using it once I needed to reselect it for every next annotation I wanted to make. Of course, I’ve found this very frustrating. Recently I’ve found out that to make any of the review tools persistent, in such a way that it can be selected once and used continuously after, it is sufficient to double click over the tool. Unfortunately this feature is concealed and I think many of the users don’t know its existence, I hope that the developers of Okular will update the tooltips of the review tools explaining how to use them correctly. This hidden feature make me save a bunch of time and I hope it can be useful for you too.