xsane freees on drop-down widgets

I have been using xsane for years on Ubuntu (now 20.04).
Using xsane 0.999-8ubuntu2.1, packages xsane and xsane-common
It started to get a problem with the drop down widgets a long time ago (I suspect it was when I upgraded Ubuntu 18-04 →20.04)

Depending on which type of scan (mainly with the option multipage), xsane freezes when trying a selection with the different drop down menus, and can only be killed manually.
If one uses the keyboard (Tab to select the menu, space-bar to open the selected menu and arrows to select an option), it works ok. But to select the size in the preview window, one needs to press Tab 11 times to reach it… very unpractical !

Indications :

Launching xsane on the command ine, I get the error
IA__gdk_drawable_unref: assertion 'GDK_IS_DRAWABLE (drawable)' failed
but everything seems to works normally using the "save" option.

If I select “multipage”, then try to adjust the resolution with the drop down menu, xsane freezes,
and the terminal issues a big number of identical lines :
(xsane:63159): Gtk-CRITICAL **: 18:02:07.788: IA__gtk_widget_event: assertion 'WIDGET_REALIZED_FOR_EVENT (widget, event)' failed

I prefer launching xsane form the command line, so that I can quit with Ctrl-C. Otherwise, it has to be killed from the command line when it freezes that way.
Here is my command to kill xsane:
sudo kill $pidof(xsane)