- Need to create a caret before calling ImmSetCandidateWindow()
this is a work-around of a bug with MS PinYin.
- Caret is created when we receive StartComposition()
and is destroyed when we receive EndComposition()
- impact only in WinXP with MS PinYin
r=shanjian sr=jst a=chofmann/dveditz
git-svn-id: svn://10.0.0.236/branches/MOZILLA_1_0_BRANCH@130410 18797224-902f-48f8-a5cc-f745e15eee43