That seemed to work for a while... but nope the black backgrounds are appearing in the Properties window [grr]
I have Windows 8.1 x64 I tried installing the x32 version, but same problem.
EDIT: I even tried downloading and installing Java separately (Java SE Runtime Environment 8u92) and installing the version that does not have JRE, but that had the same problem - if anything it is worse and goes wrong more frequently.
I even tried installing over the top of the x64 installation, which allowed me to put yEd into a different directory but.... SAME PROBLEM!
The slight clue is that even after I uninstall, yEd seems to have remembered that I wanted grey dashed lines to the default. i.e. It is NOT uninstalling cleanly. I tried removing lines from REGEDIT that contained yEd but that didn't seem to make any difference. :^[
Any other suggestions?