Cannot use visual editor after dragging a WP_Editor container

[flixos90]

When a WP Editor is placed inside a draggable element and that element is dragged (using JavaScript), the visual editor of that editor is not usable any longer: Its content disappears and it's no longer possible to even click into the editor frame.

The first time I saw this happening was inside a custom element that I made draggable using the jQuery UI Draggable plugin. After that I also tested the editor inside a regular WordPress meta box, and when I dragged that metabox, the same issue occurred, so it the bug was not related to my own JS implementation.

While investigating, I discovered that this seems to be a general problem of TinyMCE - I couldn't find a proper solution yet though.

[ocean90]

Duplicate of #19173.