This tests copying and pasting text does not remove non-editing style in the destination.
To manually test, copy "hello world" below and paste it in the box below. The blue border should stay after the paste.
Before copy:
| <b>
| style="border: solid 5px blue;padding: 5px;"
| <br>
After paste:
| <b>
| style="border: solid 5px blue;padding: 5px;"
| <i>
| style="font-weight: 400;"
| "hello<#selection-caret>"