CiviReport Change: $this->_options array partially ignored

CiviReport offers developers a way to add options to the report form that are unrelated to the columns to be added to the SQL call. Several of the core reports make use of this feature including the "Participant List count report". Adding a checkbox to the report no longer works in the way it used to.

To reproduce on demo:

• Go to http://d46.demo.civicrm.org/civicrm/report/event/participantlist?reset=1
• Click on the options tab.
• Choose the option "Blank column at the Begining" (Also note spelling)
• Result: It doesn't create a blank column at the beginning.

It is not limited to this report. Other reports in core and one we have in the tax extension are affected.

I also wonder is this still the recommended way to add additional options to reports?
I found mention in this issue (https://issues.civicrm.org/jira/browse/CRM-15695) of a hook to alter the report columns: CRM_Utils_Hook::alterReportVar('columns', $this->_columns, $this)

If this hook is recommended however it is not documented on the wiki: http://wiki.civicrm.org/confluence/display/CRMDOC/Hook+Reference