I see this on ElementaryOS 0.4 release with updates as of 2017-01-15 and have been for a while.
In my case, my Dell XPS 13 9360 has a 13.3" 3200x1800, so the high-dpi resizing works fine on everything. When plugging an external monitor, it removes the high-dpi resizing on everything except certain apps, eg gedit.
I see this on ElementaryOS 0.4 release with updates as of 2017-01-15 and have been for a while.
In my case, my Dell XPS 13 9360 has a 13.3" 3200x1800, so the high-dpi resizing works fine on everything. When plugging an external monitor, it removes the high-dpi resizing on everything except certain apps, eg gedit.