remove line unter tabs, it is ungly in the default UI

git-svn-id: http://svn.net-core.org/repos/t-engine4@3550 51575b47-30f0-44d4-a5cc-537603b46e54

game/engines/default/engine/ui/Tab.lua

@@ -60,7 +60,7 @@ function _M:generate()
 
 	self.rw, self.rh = self.title_w, self.title_h
 	self.frame = self:makeFrame("ui/button", self.w, self.h)
-	self.frame.b2 = self:getUITexture("ui/border_hor_middle.png")
+--	self.frame.b2 = self:getUITexture("ui/border_hor_middle.png")
 
 	self.frame_sel = self:makeFrame("ui/button_sel", self.w, self.h)