Outline of labels/strings drawn to desktop

* Rather than duplicating the decision taking logic involving wheter or not to draw
the outline or glow in every replicant, update be_control_look to make it more
generic.
* The Monitoring of the background preferences is now only done in Tracker (where it
was already being done).
* Add a BControlLook::B_IGNORE_OUTLINE flag to avoid this new behaviour.
* Remove that said logic from ActivityMonitor and use be_control_look.
* Use the ignore flag in DeskCalc to avoid the outline in its case.

Should fix #7716, #7291.

headers/os/interface/ControlLook.h

@@ -70,6 +70,7 @@ public:
 		B_HOVER				= 1 << 3,
 		B_DISABLED			= 1 << 4,
 		B_DEFAULT_BUTTON	= 1 << 5,
+		B_IGNORE_OUTLINE	= 1 << 6,
 
 		B_BLEND_FRAME		= 1 << 16
 	};
@@ -271,6 +272,8 @@ public:
 									const rgb_color& base, uint32 flags,
 									const BPoint& where);
 
+			void				SetBackgroundInfo(BMessage msg);
+
 protected:
 			void				_DrawButtonFrame(BView* view, BRect& rect,
 									const BRect& updateRect,
@@ -362,6 +365,11 @@ protected:
 									const rgb_color& bevelTopColor,
 									const rgb_color& bevelRightColor,
 									const BGradientLinear& fillGradient);
+private:
+			bool				fCachedOutline;
+			int32				fCachedWorkspace;
+			BMessage			fBackgroundInfo;
+		
 };
 
 extern BControlLook* be_control_look;