Yes, I agree that it's subtle. But it is so to avoid creating visual noise. Please also notice that these icons change when you scroll the text using Left-Right buttons (or with Left Click + Scroll). 

Thanks for pointing out that this is not described in help. Of course it should be there, I'll add the description of this behavior.

But there is already one:

Fixed in 2.6.1

Actually completed and released long ago

Yeah, the design process is like that - full of compromises ;)

Time and Link tabs would offer access to quick filtering notes by date/time (instead of the current nearly defunct search by date) and by the Link (will present the alphabetically sorted list of 1st level domains).