switching to visual mode and going down puts the cursor one to the right of where it should be

[alisonatwork]

If you go into visual mode using v, it moves the cursor one to the right to highlight one character of text. This is not the same as vim behavior, but not completely weird given the way selections work in normal GUI apps. What is weird is that if you then go down one line using j, it moves the cursor one more column to the right. And if you go up two lines with kk it the moves the column back to the left again. Alternatively if you start by going up using k, it stays in the correct column, but then when you go down with j it jumps one more column to the right.

There is a bunch of code in the extension that tries to figure out the selection start and end points and will nudge them back or forward one character given some context. I think there is an off-by-one problem in this code, I just haven't had enough time to methodically go through it and figure out where that problem is.