By default, all edges of the screen are dead in XFCE. Also, the default panel location (in the center) wastes the usefulness of corners. Sensitizing the very edge of the screen enables much faster navigation with the mouse, as I can just throw the mouse to a corner and get the icon I want. Ideally, the main menu should default to being in one of the four corners, with the corner pixel actually active. The simpler, immediate fix (which wouldn't interfere with current aesthetic choices) would be to make the edges of the taskbar and of the panel sensitive so that throwing the mouse to the bottom or top of the screen allows you to select icons on these two panels.
Assuming I'm understanding what you mean by "the edges are dead", the panel and taskbar in CVS already allow you to click buttons with the mouse at the extreme edge of the screen. As for default panel placement, that's an homage to CDE, which Xfce is somewhat loosely based on (looser by the day, I suppose). (By the way, there's no "simple" fix to the dead edges problem. You either have to implement somewhat-complex event forwarding code to foward mouse clicks to the buttons, or you have to remove all border and padding around the buttons, which some people think looks ugly. I believe Jasper opted for the latter solution.)
You have indeed understood what I meant by the edges being dead -- I'm glad to hear the fix is in CVS. I assumed the solution would be simple because the GNOME panel has handled this for a while now -- so I figured it must be doable with the underlying GTK toolkit stuff. I guess I was write about the default center positioning -- again, not a big deal since it's configurable. Though I would like to be able to make the panel grow to be as wide as my screen (otherwise it looks kind of funny if you align it left or right rather than center) -- and I'd like to get rid of the grippies on the panel so that the menu could be at the absolute corner of the screen (right now the left-hand pixels allow me to grab and move the panel; the actual button for my menu is a bit to the right). All minor details -- thanks for great software. xfce makes a gtk-based interface usable and snappy on my old machine (the full GNOME desktop, while beautiful, can drag to a halt pretty fast!).