if I add an event in the signature track and I double-click on the 4/4 text to change it, I see an annoying flickering of the cell. Am I alone?
Your sig is missing your Cubase version. But here, not seeing that.
yes, I forgot to mention I am using 7.5 (I will update my signature). I added a .gif showing the problem. Note that in the .gif the flickering is much more slower as it records one frame every 8 (or something like that).