Some keys like key down are composed from multiple characters. Normally when the key down is pushed, 3 characters are written into stdin. These 3 characters are read by InputStream::read operation at once and then decoded to the Key.DOWN constant.

However there is no guarantee that InputStream::read operation returns all the 3 characters at once. It can return only first character and then remaining two. This actually happens in one test on Solaris and HPUX, where stdin is emulated by PipedInputStream.

If the aforementioned situation happens, pushing of key down is decoded as pushing of two maybe three keys - ESC and some other key(s).

The issue has low priority, because this behavior wasn't observed in real terminal with real input. It affects only testing.