Hello @Z!
Thanks for the report, and though issue. Sometimes we thrive to keep backwards compatibility as there will be a considerable number of upgrading users. But in this case this made Ext.NET API differ from ExtJS documentation.
Maybe that's not a good idea to "fix" this in version 3 still. But definitely in a next major upgrade, and probably worthy in version 4.
In fact, this difference reflects in documentation at least since version 1 to 2 upgrade. Only back to
ExtJS 3.4.0 the parameter used to have
Tab in it. From
ExtJS 4.0.0 onwards, we see
Card.
Well, we have created issue
#1403 to track this problem, and we'll update here as soon as we implement this in Ext.NET. The problem does not limit to the
beforetabchange event, but other events using
card in part of the parameter names.