I'm not sure if this is the right place. But I think the following would be really nice to have:
"Close all tabs button". Closes all the tabs currently open.
A way to distinguish between even sheets and layouts on the tabs. Maybe something like [E] Event sheet 1, <img src="smileys/smiley27.gif" border="0" align="middle" /> Layout sheet 1.
Some auto save features, I would love to be able to set the IDE to auto save on every "run layout".
And lastly, not so much IDE. But could you make a way to override the default icons used for the various export methods. EG. on the project, link my own "logo.png" for the html 5 icon, rather than having to manually replace it every time I export?