cannot input space in noseeing input method

[frozenmouse]

I expected that hitting the space bar without any key code is to output a space.
It's very inconvenient, and most of the IMEs will output a space character in this situation.

Steps to reproduce:

1. select 嘸蝦米 as current input method
2. hit space bar, and it will respond "找不到對應"; nothing is being inputed.