Vietnamese IME word composition bug

[ducminh03]

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Windows Terminal version (or Windows build number)

Windows Terminal 1.10.2714.0

Other Software

• Microsoft Windows [Version 10.0.22000.194] (though I believe this also occurs back to Windows 10 1903, which is the first version of Windows where Vietnamese Telex IME is first introduced)
• Powershell 7.1.4 (x64)

Steps to reproduce

1. Add the Vietnamese language and 'Vietnamese Telex' keyboard layout
2. Open Windows Terminal, then switch to PowerShell
3. Switch to Vietnamese Telex keyboard layout
4. Type 'Xin chaof' (including the apostrophe) then press Enter

Expected Behavior

The sentence 'Xin chào' is written to the console, with normal word composition. (The screenshot is took in conhost)

(Note for non-Vietnamese: the 'f' denotes the grave on the main vowel, which, in this case, is the 'a')

Actual Behavior

The IME composition works normally for the first syllable Xin. However, after pressing the 'c', the IME suddenly sticks the previous syllable at the beginning when composing, which breaks normal Vietnamese syllable structure. Therefore, when pressing the letter 'f', the IME then decides to append an 'f' instead of putting a grave on the 'a'. All of these result in the output of 'Xin Xinchaof'.

Somehow when composing the following words, the keystroke of the previous composition is retained. After typing Xin, then pressing Space and the 'f', the grave is put on the 'i' of the previous syllable 'Xin':

The problem seems to come from the IME itself, since it is a relatively new piece of software. However, it would be nice to explain why the problem does not occur on conhost.

[msftbot[bot]]

:tada:This issue was addressed in #13678, which has now been successfully released as Windows Terminal Preview v1.15.228.:tada:

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