[Evolution] blurred font rendering on evolution 3.12.11?

[Nicolas Hüppelshäuser <nicolas praxis-nh de>]

Hi everybody!

I'm having trouble with blurred font rendering in evolution 3.12.11 on
my ubuntu-gnome 15.04.  I installed 15.04 on a new machine and restored
an evolution backup made on the old ubuntu-gnome 14.04 machine.

All fonts in the email preview section of the main window (lower right)
look blurred.  In email windows (which open by double-clicking on an
email in the message list) the email text and headers look blurred as
well.

It does not matter whether the email is html or plain text format and it
does not matter which font I configure in the settings.  By the way:
when editing a new message, the font is sharp (both html and plain text
editing).  Most other windows are sharp as well.  Just found another
window with blurred font: in the task-window the lower right showing the
description of the task.

I am a bit at a loss here, since I'd expected to find some search
results on that matter...

I could attach a jpg-file if helpful.

Is this a known issue?  Is there a work-around?  Would it help to update
to the newest stable evolution version?

thank you in advance
    Nicolas