Strange problem with transaction editing auto-complete

[jmk]

Hi all,

I had a very strange behavior surface today while I was entering
transactions. I use the keyboard autocomplete feature to quickly
categorize things (e.g. I type "ex:fo:di" to autofill to
"Expenses:Food:Dining"). Well for some reason this has become really
erratic. Sometimes it will work as it always has for years, but
sometimes the highlighted text in the input box will become unselected
and place my cursor at the end and everything I type after that is
translated literally and not used to match a category. In the above
example I might end up with something like "Expenses:Fo:Diood" --
GnuCash decided to unselect the text right after I typed the 'o' and
left the autofill text at the end. It's very weird and hard to explain.

I haven't had any input problems in any other applications.

I GC 2.6.12 on Unbuntu 16.04 running KDE Plasma 5.8.5.