No.
Self = 1 form only!
That would “work” only, if I repeat that 58x on 58 different form.
This: SaveMyFormsPosition( TForm(TsSkinProvider(tsTitleButtons(TsTitleButton(Sender).Collection).Owner).Owner ) );
works universally. It was enough to do it once, and add sSkinProvider1TitleButtons0MouseUp on the fly to each runtime-created button.