notify-osd should look into panel gconf keys such as:
/apps/panel/toplevels/top_panel_screen0/orientation
/apps/panel/toplevels/top_panel_screen0/size
There are a lot of cases here that should be taken into account, including cantered or justified panels, autohidden panels, etc. To be on the safe side, I would do all of these checks for all "toplevels", since a user might have dragged the panels all over the screen and perhaps has swapped the bottom and top panel.
notify-osd should look into panel gconf keys such as: toplevels/ top_panel_ screen0/ orientation toplevels/ top_panel_ screen0/ size
/apps/panel/
/apps/panel/
There are a lot of cases here that should be taken into account, including cantered or justified panels, autohidden panels, etc. To be on the safe side, I would do all of these checks for all "toplevels", since a user might have dragged the panels all over the screen and perhaps has swapped the bottom and top panel.