visual inheriitance does not work with the FNCPageControl, things get messed up totally when inheriting from a form that has a pagecontrol.
forgot to say, it is FMX
This is unfortunately a technical shortcoming, in the way the page control is created. Its page management is different from that of a normal TPageControl, therefore it always needs to be handled directly on the main form. I'll investigate the possibilities of creating a workaround.