In the case of typing in our 'virtual' keyboard, `keypress` is not a valid reference for checking if a character was added (actually you can tap on a key, swipe the finger out of the keyboard, and nothing should happen). In this case `input` or `keyup` let us know if a new `character` was added, and show the banner in that case for notifying that we have reach the max. lenght of the subject.
Currently in master, only 'tapping' any key of the virtual keyboard shows the banner, which IMHO is not correct.
@rwaldron Probably is the same for the bug you are solving in https://github.com/mozilla-b2g/gaia/pull/15118, maybe is better to check if the keyup happens, instead of only taking into account the keypress action.