Space inserted when switching languages on Japanese keyboard with OSX

Pressing the hiragana/katakana/romaji button on a Japanese keyboard (which is by default bound to toggle between input languages) switches the input language, but also inserts a space into the QTextEdit widget. This used to be a problem for command+space as well, but that was fixed in some previous release. This makes inputting more than one language for Japanese users quite inconvenient, as they have to manually erase the space every time they switch input languages.