Black bar when opening already maximized Application on Gnome 3.18

[metinkale38]

Hey,

have a problem, which is 100% reproducible for me...

I directly installed from https://extensions.gnome.org/ and have Ubuntu Gnome 16.04

Each time i start a already maxmized Application i get a black bar under the top status bar (http://fs5.directupload.net/images/160802/5c6vg957.png)
If i unmaximize and remaximize its gone and everything is fine...

I use the Numix theme, but its the same on other themes...

In the Extension Settings the "alternate method to hide..." is activated, if i disable, the extension is not working anymore (gnome disables it automatically because of issues)

[skewty]

Bug also affects Gnome 3.20 with Adwaita theme.