Oh my goodness! So it IS a browser issue after all!
The above .capx did not even display correctly in Firefox 30.0 (no buttons were shown), so I tried it in Chrome 35.0 and it worked first time!! <img src="{SMILIES_PATH}/icon_e_surprised.gif" alt=":o" title="Surprised">
I then went back to my original URL (now updated to include your script), and tried this in Chrome as well and it also worked first time. <img src="{SMILIES_PATH}/icon_eek.gif" alt=":shock:" title="Shocked">
I then updated Firefox to version 31.0 to match yours (just in case it was a feature unsupported in Firefox 30.0) and then tested the original URL as well... but it still didn't work!
Bizarre! Please can you test my URL to see if the print function works for you in your browser? <img src="{SMILIES_PATH}/icon_e_confused.gif" alt=":?" title="Confused"> I am very VERY confused...
http://angelserver.in/html5/dinotrain/
Thank you for all of your assistance, I really appreciate the time you've taken to help me resolve this issue.