Configuring Evolution toolbar icons

[Patrick O'Callaghan]

I'm using Evo 2.30 on F13 under KDE. The main toolbar is shown in the
attached screenshot. In earlier versions of Evo the icons were different
and I've done nothing explicitly to change them.

My main quibble is that the Trash and Junk icons are almost identical,
which causes a lot of visual confusion when in use. See if you can guess
which is which. No, neither can I without hovering the cursor.

How can I change this? I've already asked on the Evo list and no-one
seems to know. It must be some theme magic, but where?

poc