This is caused by windows 10. It happens with pretty much any window you dock a screen edge. Windows 10 has an invisible border that replaces the old window border (like from windows 7, etc.). I recall there being a registry tweak to fix it, but when I tried it, the grip area to resize a window became 1 pixel wide and impossible to grab.
Here is a fairly well laid out description of the problem:
This is caused by windows 10. It happens with pretty much any window you dock a screen edge. Windows 10 has an invisible border that replaces the old window border (like from windows 7, etc.). I recall there being a registry tweak to fix it, but when I tried it, the grip area to resize a window became 1 pixel wide and impossible to grab.
Here is a fairly well laid out description of the problem:
https://superuser.com/questions/1098708/is-it-possible-to-turn-visible-the-invisible-windows-borders-of-windows-10
And some people trying to make somewhat of a fix:
https://autohotkey.com/boards/viewtopic.php?t=26514