panel_items : fixed hide/unhide of baterry and systray

git-svn-id: http://tint2.googlecode.com/svn/trunk@560 121b4492-b84c-0410-8b4c-0d4edfb3f3cc

src/util/area.h

@@ -104,6 +104,10 @@ int resize_by_layout(void *obj);
 // set 'redraw' on an area and childs
 void set_redraw (Area *a);
 
+// hide/unhide area
+void hide(Area *a);
+void show(Area *a);
+
 // draw pixmap
 void draw (Area *a);
 void draw_background (Area *a, cairo_t *c);