How do I keep a window open in front of other windows?
Whenever you have multiple windows open, is there a way to keep one window on top, or at the front of the others?
Solution 1:
Right-click on the title bar of the window and select “Always On Top”.
Solution 2:
In Gnome some applications (like Vivaldi browser) override the official gnome window and as the result the rightclick does not work. In these cases you can press Alt+space to see the window menu and then you can click the "Always on Top" or use arrow keys and Enter key to select it.
This answer was based on this thread.