Created attachment 8862656 [details] Testcase Using the testcase in Nightly, the "selectionchange" count only increases _once_ when inputting text at the end (and only at the end) of the <textarea> field.
Perhaps, this occurs when selection is collapsed at start of the trailing <br> element. I think that editor should collapse Selection at end of the end of the text node. (So, this might be an editor's bug.)
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