ibus-hangul <Space> and <Enter> keys problems on Qt5 applications

Please see the ibus bug.
http://code.google.com/p/ibus/issues/detail?id=1726

I noticed QT provides libibusplatforminputcontextplugin.so and the "ProcessKeyEvent" DBus method is used as sync mode.
When ibus-hangul has a preedit text with a Hangul string and type Space or Enter key, "CommitText" DBus method is sent with the Hangul string during "ProcessKeyEvent" DBus method is called with Space or Enter. But since "ProcessKeyEvent" is sync mode, "ProcessKeyEvent" finishes before "CommitText" finishes.

I'm thinking now async "ProcessKeyEvent" is the solution to fix this. Maybe ibus-qt is light-weight and does not have this issue.