characters in selecting range disapear

[kyuwoo-choi]

Browser: IE11

CodeMirror: 5.30.0 (I can reproduce this issue using demo on http://codemirror.net/ too at this moment)

Steps:

1. write some korean words(may be multi type languages)
2. backspace, delete some characters
3. write korean characters again
4. try select a range using mouse
5. selected range deleted
6. later on, the characters in range will be gone continually

[marijnh]

Thanks for your report. I may be a while until someone sets up an IE11 with Korean IME to debug this. If you want to look into it yourself, the problem probably lies somewhere in the composition event handling in src/input/TextareaInput.js -- possibly it is failing to exit composition mode, either because the browser isn't sending the right events, or because of a bug in the CodeMirror code.

[kyuwoo-choi]

@marijnh I've looked into it.
It seems that resetting textinput failed.
The TextareaInput.reset() is called on the step 4 above.
And cm.somethingSelected() returns false on IE while it does true on Chrome

https://github.com/codemirror/CodeMirror/blob/2c741bd6742678f67e812307b2f78db4f4566d9d/src/input/TextareaInput.js#L138-L151

End up with passing condition below
https://github.com/codemirror/CodeMirror/blob/2c741bd6742678f67e812307b2f78db4f4566d9d/src/input/TextareaInput.js#L215
and executing code below with wrong values.
https://github.com/codemirror/CodeMirror/blob/2c741bd6742678f67e812307b2f78db4f4566d9d/src/input/TextareaInput.js#L234-L247

But I have no idea how to fix. may be similar to how you fix for #1730
I need you to guide me.

[adrianheine]

This is one of many issues which are difficult to solve with the fundamental approach currently taken by CodeMirror.

We are working on a rewrite (CodeMirror 6) that will overhaul input handling and should address this issue, and we are currently raising money for this work: See the announcement for more information about the rewrite and a demo.

Note that CodeMirror 6 is by no means stable or usable in production, yet. It is highly unlikely that we pick up this issue for CodeMirror 5, though.