An older version of subl seems provide a bad support of input method, and the latest version even seems remove it.
I hope sublime will support input method correctly, since it's a requirement for all CJK user, which sublime developer might ignore.
I'm developer of Fcitx, an input method framework on linux, for some technical details:
1. do not grab key event before input method.
2. do not eat key event it doesn't use.
Input method should always have the highest priority for key event, and by default input method use "ctrl + space" as default trigger key, which all application should avoid.
Thanks.