Created attachment 360480 [details] [review]
background: Drop dead background screenshot code

cc-background-panel.c contains:

gdk_screen_get_monitor_geometry (gtk_widget_get_screen (widget), primary, &data->monitor_rect);
gdk_screen_get_monitor_workarea (gtk_widget_get_screen (widget), primary, &data->workarea_rect);

Which both get the same result due to the following changed in GTK 3.22 

void
gdk_screen_get_monitor_workarea (GdkScreen    *screen,
                                 gint          monitor_num,
                                 GdkRectangle *dest)
{
  ...

  /* FIXME */
  gdk_monitor_get_geometry (monitor, dest);
}

Due to these values being the same a screenshot of zero size is requested. This causes a slight delay showing the background, but doesn't change the content. This may be a bug in GTK+, or this screenshot code is not required anymore.

I've attached a patch that removes it if we don't need it anymore.

(Bug was found migrating to non-deprecated API which then did get the correct workarea and the background looked broken).