Cannot delete horizontal rule via backspace

[Lynne Kues]

Put the following html into editor

<p>

This is some text</p>

<hr /> <p>

This is some more text.</p>

<p>

Another paragraph</p>

Place cursor at beginning of "This is some more text." line. Press backspace. The horizontal rule is not removed, cursor remains in the same place. Press backspace again. On FF, cursor moves to unexpected location (after the first line). Put cursor at beginning of the line again. Press backspace. Nothing happens. Press backspace again, finally the hr is removed.

Observed in 3.4.2 and 3.6

[Jakub Ś]

Reproducible from CKeditor 3.0 for FF3 and FF4.

IE also behaves strangely when applying the above TC (from CKEditor 3.0).

IE9 and IE8 - It's not possible to remove horizontal line with backspace, no matter how many times you press it.

IE6 and IE7 - You have to press backspace two times quickly to remove hr. If you press it once text will go line up for a moment and go back to previous position.

[Jakub Ś]

#4867 was marked as duplicate.

In latest Firefox 60 you still need to press backspace 3 times to delete hr element.