maybe you're just bad at drawing lines straight up and down. I can't believe you drew a line so straight with your mouse that the jitter is even measurable in comparison, although trying that was a good idea. There is no way to adjust the sensitivity. I've never heard anyone with this complaint before. The complaint is usually "I hate drawing runes, is there a lua script that will let me hit buttons".

That may not have been the logical place. I dont know where "install directory" is but use process monitor to watch which ini file desmume is reading. It may be reading a broken one with a memory of window position which is massively wrong. delete that ini file once you find it. Or launch desmume and hit alt+space, M and then use arrow keys to move the window back into a visible position

your GPU drivers are broken.
make an ini file containing only this

[Video]
Display Method=3

and see if desmume will boot. if that doesnt work, try other values 0,1,2

--windowed-fullscreen

Yes, it's possible. Hope this answer brings you pleasure and good feels.

Desmume doesn't make backups of your files for you (although some emulators do). You or your OS make backups of files. You need to institute a backup and recovery strategy if you're going to invest a lot of time in creating data.

Then your file recovery tools are inadequate. You will need to make more extensive manual backups in the future.

This isn't a question about desmume, it's a question for your "pc clean" vendor. Ask them how to get back "deleted unused files"

the video solution will be on youtube.
use file > import backup memory.
If that doesn't work, then your source backup memory is garbage. Wrong extension, wrong format, something wrong with it.
To get from desmume, use file > export backup memory and try both of the options depending on your needs

im out of ideas. all that's left is for you to get on IRC (#desmume on freenode), run teamviewer, and wait for me to appear to remote debug it.

use notepad

What do you think?