Cocoa port :

- Window creation at preferred size
  Implement in Ghost the use of Cocoa functions to get the maximum visible rect (size and position) for the window contents (all screen excluding dock, top menu, and window title bar)
  Thus Apple specific code in window creation (wm_window.c & wm_apple.c) is no more needed => removed in case of Cocoa build

- Alert on exiting despite unsaved changes
  Add to GHOST method to maintain an all platforms (not apple specific anymore) status on unsaved changes
  Update GHOST_SystemCocoa to use this for asking or not user to confirm exit without saving changes

intern/ghost/GHOST_IWindow.h

@@ -161,6 +161,19 @@ public:
 	 */
 	virtual GHOST_TSuccess setState(GHOST_TWindowState state) = 0;
 
+	/**
+	 * Sets the window "modified" status, indicating unsaved changes
+	 * @param isUnsavedChanges Unsaved changes or not
+	 * @return Indication of success.
+	 */
+	virtual GHOST_TSuccess setModifiedState(bool isUnsavedChanges) = 0;
+	
+	/**
+	 * Gets the window "modified" status, indicating unsaved changes
+	 * @return True if there are unsaved changes
+	 */
+	virtual bool getModifiedState() = 0;
+	
 	/**
 	 * Sets the order of the window (bottom, top).
 	 * @param order The order of the window.