IE 10 and up: Language Switching Buttons do not change content in TinyMCE fields

[johnclause]

Apparently same issue reported in a few places:
https://wordpress.org/support/topic/unstable-under-ie11
https://wordpress.org/support/topic/buttons-dont-change-content-in-tinymce-fields-in-ie10-possible-fix

In short:

1. The language switching buttons are, most of the time, not switching the content in TinyMCE.
   When editing content in WYSIWYG-area and updating the post, all changes are lost.
2. A, sometimes, working solution is to switch to the raw editor and after that use the language switching buttons, or update the post. But this is inconsistent and not stable at all.
3. No JS errors is reported in the F12 console.

Other user observation:

Not sure if this is actually a bug (maybe someone can confirm) or some plugin conflict BUT, after hacking away at admin/js/common.js I discovered the following:

• window.addEventListener('load', function(){ ... }); works to register tinyMCE.editors in Chrome but not in IE (weird?)
• "I have no idea what i'm doing but it's fixed": wrap everything up from inside the 'load' function in a setTimeout() with 1000 to give IE a chance to "LOAD" load the loaded page. (sheesh)

[johnclause]

Please, try the latest development version
https://github.com/qTranslate-Team/qtranslate-x/releases/tag/3.2.9.8

[johnclause]

I assume this can be closed, we can still write into a closed issue, or we can re-open it, if needed.