ActiveDocumentEditorChanged is not always fired correctly.
Occurs for properties of paragraph like alignment or ListId as well.
Even if a cell is aligned to center or right, the td element in the HTML has attribute align="left". The paragraph within has the proper alignment, but this is confusing. MS Word omits the align attribute of the cell and sets alignment on the paragraphs directly.
All attributes for table cell are exported to HTML regardless of whther they are added to HtmlExportSettings.PropertiesToIgnore or not.