This format is special as it doesn't have a fixed value and is registered dynamically instead. So we need to call HtmlFormatFixup(), which checks if the given custom format is actually wxDF_HTML, before comparing formats to ensure that the real value assigned to this format compares correctly to the fixed wxDF_HTML value. Closes #15280. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74997 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775