Typing ENTER yields a KEY_TYPED event (in addition to KEY_PRESSED and KEY_RELEASED events).
For some reason on Linux getCharacter() returns "\0" but should return "\r":

KeyEvent [source = WebView@19d2bed, target = WebView@19d2bed, eventType = KEY_TYPED, consumed = false, character = \000, text = , code = UNDEFINED]

This used to work, but broke relatively recently (in the November time-frame, probably).

In contrast, on Windows I get:

KeyEvent [source = WebView@135dd72, target = WebView@135dd72, eventType = KEY_TYPED, consumed = false, character = \r, text = , code = UNDEFINED]

I can debug this myself, but if someone has an idea where the problem might be that would probably be more efficient. Or, if it would be helpful, I can create a stand-alone test-case.