Enhanced curve editor :

- graphical celan up (surrounding frame deleted, histogram realigned)
- a feedback tell what point is going to move
- on Button press, the point doesn't move to the cursor anymore. Instead, the cursor
  is hidden during the drag and reappear in the same place it disappeared
- by default, a 0.5 factor is used to move the point during the drag
  (i.e. you have to move the move of 2 pixel to move the point of one pixel)
- keyboard can be used to fine tune the point position (subpixel placement) :
   - CTRL : factor = 0.1
   - SHIFT : factor = 0.02
   - CTRL+SHIFT : factor = 0.005

In the mean time, i had to create a new "Empty" cursor to hide it.
A new method has been created to easily modify the cursor of the main window.

rtgui/cursormanager.h

@@ -21,7 +21,7 @@
 
 #include <gtkmm.h>
 
-enum CursorShape {CSArrow, CSOpenHand, CSClosedHand, CSMove, CSResizeWidth, CSResizeHeight, CSResizeDiagonal, CSSpotWB, CSCropSelect, CSStraighten};
+enum CursorShape {CSArrow, CSOpenHand, CSClosedHand, CSMove, CSResizeWidth, CSResizeHeight, CSResizeDiagonal, CSSpotWB, CSCropSelect, CSStraighten, CSPlus, CSEmpty};
 
 class CursorManager {
 
@@ -33,14 +33,17 @@ class CursorManager {
         Gdk::Cursor* cCropMoving;
         Gdk::Cursor* cNormal;
         Gdk::Cursor* cCropSelection;
+        Gdk::Cursor* cAdd;
         Gdk::Cursor* cHand;
         Gdk::Cursor* cClosedHand;
         Gdk::Cursor* cWB;
+        Gdk::Cursor* cHidden;
         Glib::RefPtr<Gdk::Window> mainWindow;
 
     public:
         void init        (Glib::RefPtr<Gdk::Window> mainWin);
         void setCursor   (Glib::RefPtr<Gdk::Window> window, CursorShape shape);
+        void setCursor   (CursorShape shape);
 };
 
 extern CursorManager cursorManager;