Afloat Installer
Afloat is always on top solution on OSX, you can follow this post to understand what does it do.
Always on top in MacOS Yosemite
macOS Sierra Solution
curl https://raw.githubusercontent.com/rwu823/afloat/sierra/install.sh | sh
Installation
open your terminal then copy and paste below:
curl https://raw.githubusercontent.com/rwu823/afloat/master/install.sh | sh
input your password ββββββ
Reboot into recovery mode and disable SIP
Important !! Afloat doesn't support each app, the related discuss here #7 and #15.
Congratulation!! look at the Window menu.
Key Binding
Test
Work fine on my OSX 10.10.x and 10.11, if any issues please post it.