Bug 1820405 - Ignore bogus enter-leave by default in lg3d/qtile. r=stransky

Differential Revision: https://phabricator.services.mozilla.com/D172656

widget/gtk/nsWindow.cpp

@@ -4237,6 +4237,7 @@ static bool IsBogusLeaveNotifyEvent(GdkWindow* aWindow,
     const auto& desktopEnv = GetDesktopEnvironmentIdentifier();
     return desktopEnv.EqualsLiteral("fluxbox") ||   // Bug 1805939 comment 0.
            desktopEnv.EqualsLiteral("blackbox") ||  // Bug 1805939 comment 32.
+           desktopEnv.EqualsLiteral("lg3d") ||      // Bug 1820405.
            StringBeginsWith(desktopEnv, "fvwm"_ns);
   }();