When I open dev tools and then switch to another tab the area of the dev tools is still present as a blank space on the switched tab. It happens with all tabs opened at that moment. It didn't happen on previous releases.
To remove that blank area I have to re-open and close dev tools but doing it for all open tabs is an hard work!
version: 43.0.2442.1144 (PGO)
system: Windows 10 64-bit (WoW64)