Edge loses selection position when focused the first time

[Comandeer]

What is the purpose of this pull request?

Bug fix

Does your PR contain necessary tests?

All patches which change the editor code must include tests. You can always read more
on PR testing,
how to set the testing environment and
how to create tests
in the official CKEditor documentation.

This PR contains

• Unit tests
• Manual tests

What changes did you make?

It's just a dirty hack for Edge. I've added check in domFix to allow reselection in Edge only if the editor was previously focused. To check it I use editor._.previousActive.

The real source of the issue is buried deep in our selection. It seems that call to selection.removeAllRanges somehow prevents Edge from changing selection. The procedure for clicking the first time into editable area is:

• treat focus event as clicking at the beginning of the content
• then treat the click as a separate selection change.

Our domFix method interrupts this procedure and changes it to:

• treat focus event as clicking at the beginning of the content
• add missing bogus brs and reselect the current selection
• then treat the click as a separate selection change.

It works this way in IE. However Edge seems to stop after reselecting and does not change selection to the place of the click. But how it is connected with removing ranges – I don't really know.

As this issue is visible only on the first focus and researching our whole flow of focusing and selecting could take very long, I decided to apply some minimal hack instead.

Closes #504.

[f1ames]

Rebased onto latest major.

[f1ames]

Looks good, just two minor things to address.

[f1ames]

Rebased onto latest major.

[f1ames]

LGTM 👍