Backspace can not erase the last one character during Chinese/Japanese IME conversion (macOS)

[rebornix]

• VSCode Version: 1.12-Insiders
• OS Version: macOS

The same issue as electron/electron#9173

Reproduce steps:

1. Open any markdown file, preview
2. Go to Search Viewlet or Git Viewlet
3. Switch to Japanese IME
4. Type Japanese, and then delete
5. You have to press Delete twice when deleting last character.

[rebornix]

It's actually more severe as if there is any webview, we'll receive wrong composition events in editor as well. So if you are editing markdown files in Japanese with Preview open, you'll run into the same issue. cc @mattbierner

[bpasero]

@rebornix does this only reproduce in native input fields or also inside the editor? any clue for a workaround or fix? I fear this could block our electron update...

[bpasero]

I just confirmed that this also happens in the editor as long as there is a webview open.

[rebornix]

@bpasero when there is a webview, the composition state is not updated at all. Take below as example

• Press a, and we get ��あ
• Press Backspace, we get a backspace keydown event, however, we didn't get any composition related event.
• Press another Backspace, we get compositionEnd event.

This problem only occurs when you only have one character/phonetic radical left. For IME using phonetic composer, like Simplified Chinese and Japanese Hiragana, we can detect whether there is only one single phonetic radical left. However for IME using radical composer, like Traditional Chinese and Korean Hangul, they are behaving differently. Traditional Chinese has this issue as well but Korean Hangul doesn't. Even though we might be possible to hack it around by checking Locale/IME but it's too hacky.

The events emitted by browser align with the behavior of input box. I can't reproduce this issue with latest Chromium Version 57.0.2987.133 (64-bit).

[rebornix]

This is not just Japanese, I can also reproduce this problem with Chinese IME.

Once there is a webview, all viewlets are affected, including Editor and Integrated Terminal. cc @Tyriar

[bpasero]

Since I am not expecting a fix on our end, moving to backlog until we go for a more recent electron version.

[rebornix]

I tried to get an idea of how bad it is by writing a fresh new blog post in Chinese, thinking, writing and tweaking the content. Within 30 minutes, I wrote 900 characters and ran into this issue 7 times. Current behavior is annoying to me, it's just weird. So I'll say it's not a blocker.

Besides, once you open a webview, you'll have this issue always. It means you open Markdown Preview, and then close it, you still have this backspace issue in editor and anywhere else. The only way to get rid of it is restarting VS Code.

[bpasero]

Looks like this is a Chrome issue (as reported by Kevin here: https://bugs.chromium.org/p/chromium/issues/detail?id=714771) which means we will not get a fix until Chrome has fixed this or provided a workaround.

@rebornix given that, do you think we can add a hack to make this work or is there nothing we can do from our end?

[rebornix]

@bpasero as it's affecting native input/textarea and js events, I don't have an idea of how to hack it right now.

[chezou]

As of now, the Chromium issue has been fixed. Is there any plan to bump it? I confirm it happens on Windows/Ubuntu.

[bpasero]

@rebornix since we updated to a more recent Electron version, I think this issue is resolved. At least a fix from Chrome was backported: electron/libchromiumcontent#300

[chezou]

Has the same issue on Windows with VSCode 1.15.1.

[rebornix]

@bpasero thanks. I no longer see this issue in latest Insider (1.16-insider), so this issue would disappear from our next Stable.

[chezou]

Does this problem fix with 1.16.1?

This issue still occurs with VSCode v1.16.1 on Windows 10 using Google Japanese IME.

Video: https://youtu.be/Wq2LzSv4p1Q
This example is inputting single "の" (n-o) character deletes "量" unintentionally.