RFR: 8264728: When use chinese IME, the candidate box isn't moved with caret of JTextArea [v12]

[柳鲲鹏]

> Candidat box can moving with caret on windows version. Someone must wrote codes for linux(ubuntu), but it doesn't work, so he didn't commit the codes. Why it doesn't work, is the key problem.
> 
> 1, I wrote a example for linux:
> https://github.com/quantum6/X11InputMethod
> 
> I tried all parameters to test and as my research:
> If you use XIMPreeditCallbacks to initiate, the box can't be moved with caret.
> If you use XIMPreeditNothing, it works.
> All examples use XIMPreeditCallbacks to initiate input method and candidate box can't moving. So I understand why he didn't commit the codes.
> 
> 2, I traced the route of transfering caret coordites on windows version, then add codes for linux.
> 3, Taishan Office(like Microsoft Office Word) is running on jdk, we tested for a long time, it works OK.
> 4, I am not sure for AIX( no environment).
> 
> 
> JDK-8264728 : When use chinese IME, the candidate box isn't moved with caret of JTextArea
> Type: Bug
> Component: client-libs
> Sub-Component: java.awt:i18n
> Affected Version: 8,9,15,16
> Priority: P3
> Status: Open
> Resolution: Unresolved
> OS: linux
> CPU: x86_64

柳鲲鹏 has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 11 additional commits since the last revision:

 - Merge branch 'master' of https://github.com/openjdk/jdk into quantum6
 - Merge branch 'master' of https://github.com/openjdk/jdk into quantum6
 - Merge branch 'master' of https://github.com/openjdk/jdk into quantum6
 - Merge branch 'master' of https://github.com/openjdk/jdk into quantum6
 - Merge branch 'master' of https://github.com/openjdk/jdk into quantum6
 - Update to lastest
 - Merge branch 'master' of https://github.com/openjdk/jdk into quantum6
 - Remove tab
 - Update to latest and make code safer
 - Merge branch 'master' of https://github.com/openjdk/jdk into quantum6
 - ... and 1 more: https://git.openjdk.org/jdk/compare/a0357a3b...0ab7a467

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/13055/files
  - new: https://git.openjdk.org/jdk/pull/13055/files/02cdff34..0ab7a467

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13055&range=11
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13055&range=10-11

  Stats: 1063513 lines in 13075 files changed: 687567 ins; 289278 del; 86668 mod
  Patch: https://git.openjdk.org/jdk/pull/13055.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13055/head:pull/13055

PR: https://git.openjdk.org/jdk/pull/13055