#1488 Always align IME candidate window to start of composition string

[Neil Hodgson]

The IME candidate window is currently aligned to the start of any target text in the composition string on Win32 and Qt but not on GTK. When there is no target text in the composition string then the candidate window is aligned to the start of the composition string.

Behaviour is different between platforms. Target alignment is seen as adding unnecessary complexity. It may be difficult or impossible to implement target alignment in all cases. Other issues touch on this: [#2135], [feature-requests:#1300].

The proposed change is to remove code that aligns the candidate window to the target text so that the candidate window is always aligned to the start of the composition string. This is simpler, more consistent and more explainable.

Patch from @johnsonj.

[Zufu Liu]

I'm fine with this change as only Japanese IME is affected (Chinese IME composition string never has target inside).

[Neil Hodgson]

Committed as [a04edd].

[Neil Hodgson]

Committed as [a04edd].