On Ubuntu 16.04 LTS I have used simple keyboard shortcut to set property Always on Top (Nautilus window as example):
In standard Ubuntu 18.04 LTS with GNOME Shell I can press Alt+Space:
but it does not react to t.
Seems to be a real bug 1710421 since 17.10.
How to enable such menu accelerators/mnemonics in standard Ubuntu 18.04 LTS?
On GNOME Shell it is impossible! Welcome to the new brave world with unpredictable limits and problems!
To get these shortcuts on Ubuntu 18.04 LTS and 20.04 LTS in place you can switch to:
Unity - installable with
sudo apt-get install ubuntu-unity-desktop:
GNOME FlashBack - installable with
sudo apt-get install gnome-panel:
MATE Desktop Environment (my favorite, as it avoids GNOMEs Hell) - installable with
sudo apt-get install ubuntu-mate-desktop^:
xubuntu-desktop^) does not have mnemonic for Always on Top, but usable and looks very nice:
cinnamon-desktop-environment) have all necessary mnemonics:
kubuntu-desktop^) have mnemonics, they may be accessed from Alt+F3 (so called Window Operations Menu) - for example to keep window above others you need to click Alt+F3, M (for More Actions), A (for Keep Above Others) and menu is rich:
openbox), LXDE / LXQT / Lubuntu (
lxqt) have mnemonics, they are accessed with Alt+Space:
ubuntu-budgie-desktop^) have mnemonics, they are accessed with Alt+Space: