Of course, I should have better explained.
Previously, I had received an internal error message whenever I chose a template within the template popup window after following therebechips’ code (#9 in this thread).
So where the original code called for
src : \"/assets/templates/images-row-1-left.html\"
For pre-evolution versions I used:
src : \"../assets/templates/images-row-1-left.html\"
For evolution1.0 I used (entire template code inserted line #256):
src : \"assets/templates/images-row-1-left.html\"
Apparently, the difference depends upon where tinymce.functions.php is called from. The above worked for me where modx is installed at the root, but the precise url will depend on how modx is configured within each environment.