Is your feature request related to a problem? Please describe.
When working with a big piece of text, I sometimes scroll down and copy some text into another tab. When switching back to the first tab, both the input and the output pane is back on top. So I don't know where I was working just now.

Describe the solution you'd like
After tab switching, scroll position should be remembere

there are frequently issues like #5646 with people wondering why their files are classified as M)odified and read/chunked again.

we could all some logging that precisely tells:

• a files cache miss (filename key not in files cache)
• a timestamp mismatch (also telling which filestamp it is ctime or mtime)
• an inode number mismatch
• a size mismatch

there should be no output for cache hi

I've been treating tuShorten/tuWiden as a string-ish conversion between UTF16 and UTF 8, so I recommend this.

Here's the code; add it to the end of every tuShorten/tuWiden function.
if (out < (original_out + out_len)) out = 0;