This is no longer an issue.

After upgrading from Ubuntu 18.10 to 19.04 the context menus now have borders but still do not have shadows. Adwaita and Yaru themes have very subtle shadows but they are more noticeable with Ambiance and Radiance.

(In reply to Asif Youssuff from comment #7)

This is no longer an issue.

Which version are you referring to? I'm still not seeing any shadows under menus on 66.0.3 (Fedora 29) and 68 alpha (firefox-flatpak.mojefedora.cz).

Note: In my case (since a few months), the border is visible, but the shadow is not.

I started to use the Plata theme, and I see this issue on the latest nightly on Ubuntu Eoan. It is really obvious with this theme because there are no borders around the menus.

I see this using the Materia theme. Materia has the following section in gtk.css; which causes the bug.

#MozillaGtkWidget menu {
border: none;
}

This is probably there for the X11 version of Firefox. Please check if the other themes have a similar section.

(In reply to Berend De Schouwer from comment #12)

I see this using the Materia theme. Materia has the following section in gtk.css; which causes the bug.

#MozillaGtkWidget menu {
border: none;
}

This is probably there for the X11 version of Firefox. Please check if the other themes have a similar section.

At least with the default Gtk Adwaita theme, the border is present, but the shadow is not. See also my comment #9.

Looks like X11 Firefox is also missing the shadows....can you confirm?
Thanks.

Martin, I used the Materia theme (mentioned in comment 12) and confirmed that the Xorg session shows a shadow, while the Wayland session does not. I am not able to confirm your observation.

IMHO the shadow itself is painted as a part of window but I was referring to additional border shaping - for instance Adwaita has rounded corners on popup windows and we don't paint that on both X11 and Wayland.

We may be able to produce default window shadows on Wayland too.

I think bug 1708136 is related here.

(In reply to Martin Stránský [:stransky] (ni? me) from comment #17)

IMHO the shadow itself is painted as a part of window but I was referring to additional border shaping - for instance Adwaita has rounded corners on popup windows and we don't paint that on both X11 and Wayland.

We may be able to produce default window shadows on Wayland too.

I had previously filed the rounding thing to bug 1560482.

Like bug 1708136 this should work in latest nightly. Please reopen if it doesn't for you.