Shell boxpointer menus don't have scrollbars when they exceed the screen height
I am using appindicator-1.0 in conjunction with Gtk+2.0 menu. Menu consist of constant items and many dynamically added items. If the screen pixel resolution is not so good as it must be then the last menu items are not visible. Ubuntu 16.04 automatically add top and bottom bars with "^" and "v" arrows to scroll menu when mouse pointer is over these bars. But in Linux Ubuntu 18.04 (and 19.04 too) such scrolling bars are not appearing.
On the other hand menu scrolling is working fine anywhere into usual GTK window with menu bar (without using appindicator). Ubuntu 16.04 and Ubuntu 18.04 use the same 12.10.1 libappindicator version.
The test c program is available in https://github.com/tetnantet/appind-test-menu-bug. It illustrates the issue. It works fine in Linux Ubuntu 16.04 and has the described above problem in Linux Ubuntu 18.04. I have checked test program in Linux Ubuntu 19.04. The result is the same as for Linux Ubuntu 18.04.
I have made bug report https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1830422 . Sebastien Bacher adviced me reporting it here too for futher handling and resolving.
Attached appind_menu_Ubuntu16.png shows that menu has native top and bottom scroll bars in Linux Ubuntu 16.04.
Attaged appind_menu_Ubuntu18.png shows that scroll bars are absent in Linux Ubuntu 18.04 (with the same program).