GNOME programs don't size properly

I have been noticing both Gnome Terminal and Gnome Files don't seem to size themselves correctly on my Primary ultrawide in landscape in the top right corner (perhaps other places too). The coloured zone area looks correct in size but when the window sizes itself to the zone it is often smaller or larger than the zone.

Here is a screenshot of both of them in their wrong size snapped into the same zone.


_Originally posted by @skewty in https://github.com/Fmstrat/wintile/issues/160#issuecomment-1656501688_

Start by reproducing the sizing mismatch with GNOME Terminal and GNOME Files on an ultrawide primary display in landscape mode, especially in the top-right zone. Compare the displayed zone bounds with the actual snapped window bounds; done means both programs consistently match the selected zone.

Written by the indexing model from the issue text.