"Always on top" option missing for Firefox/Chrome in 18.04

Solution 1:

Although answer by Levente works, but I find it too slow to be used. So here is a better alternative (based on the same fundamental).

Use super + right click on the top bar (instead of just right click) and you can see the always on top option.

This option will be accessible in non-maximised state.

Note : I discovered the method in my answer while trying Levente's method, so partial credit goes to him too.

Update 1: "The super + right click combination works in any portion of the window". Thanks to Julian Alarcon for pointing this out

Solution 2:

I am on 20.04, and have only Firefox installed: I could experiment only with that, and not with Chrome.

I could reproduce your issue: when I right-click anywhere on Firefox's window or on the top window decoration, the "Always on top" option is missing, along with other common window-manager related options.

Yet, they can be accessed; the only condition is that the window needs to be in non-maximized state.

When one moves the mouse cursor along the edges of a (not maximized) window, the cursor changes to indicate that a click-drag along that edge would start resizing the window.

When the cursor is in this resizing mode, a right-click reveals the original window-manager context menu, along with the "Always on top" option, which even works as intended.

Bonus:

The size of the drag-to-resize area is configurable:

gsettings set org.gnome.mutter draggable-border-width 20

This will give you a 20px range along the window edges to expose the desired resizing mode.