Comment 3 for bug 843237

My suspicion here is that this is because the last page (webcam) is not actually a debconf page. The gtk_ui code tries to find the last page by looking at the registered pages, and every time a page is progressed checks find_next_step to see if that was the last one.

    def find_next_step(self, finished_step):
        # TODO need to handle the case where debconffilters launched from
        # here crash. Factor code out of dbfilter_handle_status.
        last_page = self.pages[-1].module.__name__
        if finished_step == last_page and not self.backup:
            self.finished_pages = True
            if self.finished_installing or self.oem_user_config:
                self.progress_section.show()
                dbfilter = plugininstall.Install(self)
                dbfilter.start(auto_process=True)

This code matches the behavior that the bottom section wouldn't show as well as that the second portion of install, where it said "Ready when you are" hadn't actually executed.

If this assessment is correct, this will also manifest in oem config user mode immediately after the webcam page.

I can think of two ways off hand to solve this:
1) (The easy way) Make the webcam page come before usersetup.
2) (The more involved way) Make the webcam page a debconf driven page.