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 high-dpi resizing works fine on everything including all cursors in all apps.
When plugging in an external monitor, it removes the high-dpi resizing on everything except the mouse pointer in 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 high-dpi resizing works fine on everything including all cursors in all apps.
When plugging in an external monitor, it removes the high-dpi resizing on everything except the mouse pointer in certain apps, eg gedit.