Customizer: Text widget loses Visual tab data when moved from one widget area to another

[melchoyce]

I moved my text widget to a different widget area, and now the content in the visual tab is empty, and I can’t click into the text area. If I switch to text, I see the content. Throughout this, I can also still see my content in the preview pane.

If I save, my content remains. Then, if I close and reopen the Customizer, it shows back up. There are no related console errors.

This only appears when I move the Text widget from one widget area to another. If I move it around within the same widget area, it's fine.

@westonruter says:

The problem is when the control gets moved in the DOM the editor iframe needs to be re-initialized. I think we are accounting for a widget being reordered in a sidebar but not when moved between sidebars.

See attached screenshot and ​https://wordpress.slack.com/archives/C0381N237/p1509058118000165.

[melchoyce]

5.0 is only going to include Gutenberg, so I'm punting this to a future release.