The spell check plugin is amazing. The red underlines are hard to see for tired old eyes, but I found setting '3' made them thicker and easier to spot!
A quick suggestion: the spell suggestion dialog appears in the centre of the screen, where it can cover quite a bit of text. One can easily move it over, but as soon as one goes to the next misspelling, the dialog goes back to screen centre. It would be helpful it the dialog would retain the position set by the user, at least for the current session... not necessarily from one opening of the program to the next.
2023.03.30
+ add: dialog 'Misspelled word' now uses dlg_proc API - now dialog position is kept during the app session (patch by @veksha)
- fix: if user clicks another editor during long spell-checking, checking can continue the work in another editor (patch by @veksha)