It seems that using cr3runner to start Librerator wasn't such a good idea. It does start fine, but when you try to exit, strange things will happen. First, you won't be able to exit Librerator. (I think cr3runner restarts Librerator over and over.) After a couple of tries, framework restart may occur. Also, it can happen that you see the Amazon framework, but when you try to move the cursor, another cursor from from Librerator's File Chooser will pop up too, so you'll have both of them on the screen, and both will be moving. Screen contents might get mixed. Eventually, you'll need to do a hard reset. In a word, a whole lot of trouble.
The thing is, very, very rarely, it will happen to exit just fine. When I wrote K4NT instructions, I tested it (once though) and it did work fine. After Reventlov reported
this problem, it did work for me once more in more than 50 tries.
To all those who experienced this - my sincere apologies. I should've tested it more. I chose to use cr3runner because it was the only launcher for K4NT that I could find. I know that some people reported that Kite also works on K4NT, but as far as I know, there's no update package for easy instalation on K4NT. Cr3runner had it, so I thought it would be easier for non-technical users. Iņigo did report that Librerator does work with Kite, and didn't report any problems.
I don't have K4NT myself, so I have to rely on reports from others. Many thanks to Reventlov for pointing out the problem.
I edited the first post and removed cr3runner instructions.