Improve header compatibility and
code quality.
JIRA issue: CORE-19268
- Improve <imm.h> and <immdev.h>
compatibility by correctly choosing
the items.
- Use <immdev.h> instead of
<ddk/immdev.h>.
- Move INPUTCONTEXTDX, IMEINFOEX,
IMEDPI, and CLIENTIMC into
<imm32_undoc.h>.
- Adapt to these changes.
Correctly display the composition window and the candidate window.
- At update_caret function, set the position and font of the composition window.
- We don't use internal composition string. Rely on the composition window.
- Improve WM_IME_SETCONTEXT, WM_IME_CONTROL, WM_IME_SELECT, WM_IME_STARTCOMPOSITION, WM_IME_COMPOSITION and WM_IME_ENDCOMPOSITION message handlings.
CORE-11700
