I fixed this by editing ~/.config/sakura/sakura.conf to change font size with ctrl-shift-minus and ctrl-shift-equals (plus) - at that point ctrl-minus results in the ctrl-underscore key, which is what I wanted:
font_size_accelerator=5 increase_font_size_key=plus decrease_font_size_key=minus
I fixed this by editing ~/.config/ sakura/ sakura. conf to change font size with ctrl-shift-minus and ctrl-shift-equals (plus) - at that point ctrl-minus results in the ctrl-underscore key, which is what I wanted:
font_size_ accelerator= 5 font_size_ key=plus font_size_ key=minus
increase_
decrease_