It seems that using MstnElementTemplateMgr::ActivateElementTemplateByPath() does NOT update the active setting for a custom LineStyle. When I activate an Element Template that includes a custom linestyle member, when that template is activated, the linestyle is changed to 0 (zero), NOT the custom linestyle as set in the element template.
Bruce
Further investigation seems to indicate that UNLESS that custom LineStyle ALREADY EXISTS in the DgnFile, it will not be activated. I was under the expectation that IF a template used a custom LineStyle, that the activation of that template would automatically create a local copy of the LineStyle definition in the current file. It does not.