gtk-toolbar-style setting in Ubuntu 18.04 (Bionic) no longer working

[Jonathan Kamens <jik kamens us>]

I upgraded this morning from Ubuntu 17.10 (Artful) to 18.04 (Bionic).

After doing so, my toolbar buttons in GnuCash are no longer large with text below them, as they were in 17.04.

I like the large buttons with text, primarily because the graphical icons in GnuCash are completely incomprehensible to me.

I can't figure out why my customization of this setting has suddenly stopped working in Bionic.

I filed a Launchpad bug about this with additional details: https://bugs.launchpad.net/ubuntu/+source/gtk+2.0/+bug/1765401

Does anybody have any insight?

Thanks,

Jonathan Kamens