@matkodurko Somehow I have finally understood what you were talking about =D
I took a look at your idea 1: "press space to enter tag suggestion", unfortunately, there seems to be no easy way to do that in the current display component that I am using. So, you would have to use 'Enter' instead of 'Space' to submit a tag.
And secondly, on your idea 2: "unfinished typing will get 'pushed' to the right after selecting a suggested tag". It didn't happen to me, please look at below:
Click here if the image is too small for you.
As you can see from the screencast, when I select a suggested tag, whatever unfinished typing will be gone. =)
I definitely believe what you are saying but I couldn't reproduce it, if you could take a screencast like what I did and show the discrepancy, I would maybe able to reproduce it.
Anyways, I upgraded the application to be able to filter & search by author. My post is here, do check it out! Thanks!