Your comments

thanks to let me know the shortcut ctrl+backspace, 

after tried this shortcut a bit, I think it can implement better and more logical, let me explain it more here:

assume I have selected 2 notes, one has tag 'player', another has 'player' and 'youtube', I expect ctrl+backspace can shows me 'player 2' and 'youtube 1' in tags list (the number besides the tags only related current selected notes), and the 2 selected notes filtered (only show selected notes) on the notes list window

but currently, it works little bit confusion, as ctrl+backspace implement shows 'player ##' 'youtube ##' which ## is represent all the notes have these tags in current section, thus changes the my 2 selection in the note list to all the notes have these 2 tags. // so as you may see in this situation, I lost both selected notes and my expecting in tags. :)

hope my cintanote can have this in better way. 

3 years ago "planned", I doubt if this is going to happened. :( This is really important for note taking. Please do "start" this even it is "Hard". Thank you.

could cinta possible get rid of the none related tags when I choose a note, just leave the related tags there.

because I easily have 3000 of tags, and if a note related "apple" and "university", it can't be show in just one flat place of tags, I have to rolling long way from "apple" to the end, "university" to check the related tags of selected note.

hopefully I make this clear.
I think even better is show the different level colours background of tags bases the number, like delicious (V1) did, that's more easier to find which tags we tag more, and which does less.
I agree to group tags, but not group by tagging tags method (which use lots of time to organize it), but by auto groups method, like what (ver 1) used to do with tags.

here is the image give you an idea how's is the "auto group tag" work: (the second image, which is click-able to enlarge for full)

so, people can get grouped tags naturally by doing nothing extra, just collect and tag as we usually did, but with this "auto grouping tags", they got every tags groups or you can say it "be related".

and we can also manage tags for selected notes EASIER: when I select couple of notes, that I can check what's all the tags relating them from the left tag column, yes I know currently is highlighting in the left column, but if I got a lots of tags (like 3000+), I couldn't easily check all these related tags in one area, I don't even got a scroll bar for quick view. so if you can trim all the unrelated tags when you selecting notes, that will really helps.