Scintilla / Feature Requests / #1300 Stop IME candidate window moving while typing and position it better

This feature request has added issues over time. The original issue is stated here:

See the screenshort (Pinyin IME in Chrome), and some screenshorts on https://sourceforge.net/p/scintilla/bugs/2038/

At least Chinese with Pinyin IME is more like the candidate window not moved on typing, not been distracted by the moved window: the position for the best candidate item (most likely first one) is at a consistent position on typing, making pick the item easy; otherwise more time will be spent on the candidate window to watch the position changes.

There are 5 candidate window improvements discussed on this feature request along with some other IME issues.

1) Stop candidate window overlapping composition text and taskbar.
2) Position candidate window closer to composition text.
3) Stop candidate window moving while typing.
4) Align candidate window to target part of composition text.
5) Stop Google IME on Windows 7 moving while typing.

(1) was extracted into a bug [#2120].