poe.trade recently (finally) improved it's whisper feature into just 1-click just like Durian.
For this fix, no need to re-download everything. Just grab a new copy of html/assist.js.
Here's a link to version 5 in case you're looking for it.
Cheers!
For those who want to build from the source code, I've also fixed the build concerning controls-fx dependency, you should now be able to build the project using maven.