Now we add a next line with 500 characters and put the cursor at the end of it; then we use <shift-left_mouse> to decrease the font size *twice* (with text wrapping disabled and ruler-mode enabled to observe current `window-hscroll' value). We can now easily see the `window-hscroll' value is incorrect, by comparing against the
After some experiments I derived the following function that help a bit but still not a complete answer:
`my-hscroll' function can report a value that is closer to the correct hscroll value. But the error of `my-hscroll' becomes larger if we again decrease the font size, or purposely edit a line with 2000 characters.
Is there any way to get the "exact" hscroll value? Say, with pixel-wise