PanelFrameSwitcher is missing add_prefix/suffix implementations of PanelFrameHeader
Sorry for the many notifications/issues, I know you're busy and I don't mean to spam.
Not sure if it's intentional or just unimplemented but I can't add prefixes/suffixes to PanelFrameSwitcher. I'd expect the following code to work but it segfaults:
PanelFrameHeader * header = panel_frame_get_header (self->panel_frame);
panel_frame_header_add_suffix (header, 0, gtk_label_new ("test"));