BL-625: Mono PDF generation starting without clicking

So, because you here select one to start with (before hooking up a CheckChanged handler?), you suppress the actual generation of the PDF, that would otherwise happen when Mono selected one for you? I'm still a bit puzzled, because it seems like OnEnter wouldn't be limited to before UpdateDisplay...it would happen whenever the mouse entered one of the radio buttons, wouldn't it?
Anyway, I think it's tricky enough that more comment would be helpful.