I've come from Eclipse and I like IntelliJ IDEA so far. But popups has been a nightmare for me. They are too sensitive, if I move the cursor out of the popups even by one pixel, they disappear quickly.
Javadoc popups appear a bit far away from the line when they appear on the top of the cursor. It's almost impossible to move the cursor onto the popup before it disappears. It disappears immediately when the cursor leaves the line (and it can't reach the popup since it's not near).
Also, you need to move the cursor carefully on the warning/error popups in order to click 'more...'. It quickly disappears if you don't.
Hoping for a fix about it. I'm using Linux version. Don't know if it exists in Windows or Mac OSX version.