jkcheung,
The Jeeeyul Themes plugin is incompatible with MyEclipse 2017 due to conflicts with our internal theming support.
Can you please let us know what features of Jeeeyul you want to work with? We are improving our theming support and we will try to work on the missing features.
Apologies for inconvenience caused.
–Swapna
MyEclipse Support