CTextBox: add/modify methodes for screen handlings

- split hasChanged() into hasChangedPos(), hasChangedDim()
- add return value bool to enableBackgroundPaint(), enableSaveScreen()
- add clearScreenBuffer(), for unified usage in destructor and functions
- add OnAfterRefresh() as a signal/slot handler, this allows to use
  external methodes as callbacks after painted text

src/gui/widget/textbox.h

@@ -62,7 +62,7 @@
 #include <driver/fb_window.h>
 #include <gui/color.h>
 #include <gui/customcolor.h>
-
+#include <sigc++/signal.h>
 #define TRACE  printf
 #define TRACE_1 printf
 
@@ -81,7 +81,7 @@ class CBox
 		int iHeight;
 };
 
-class CTextBox
+class CTextBox : public sigc::trackable
 {
 	public:
 		/* Variables */
@@ -110,6 +110,8 @@ class CTextBox
 		void reSizeMainFrameHeight(int maxTextHeight);
 		
 		bool hasChanged(int* x, int* y, int* dx, int* dy);
+		bool hasChangedPos(int* x, int* y);
+		bool hasChangedDim(int* dx, int* dy);
 		void reInitToCompareVar(int* x, int* y, int* dx, int* dy);
 
 		/* Variables */
@@ -179,8 +181,9 @@ class CTextBox
 		void    refresh(void);
 		void    scrollPageDown(const int pages);
 		void    scrollPageUp(const int pages);
-		void    enableBackgroundPaint(bool mode = true){m_nPaintBackground = mode;};
-		void    enableSaveScreen(bool mode = true){m_SaveScreen = mode;};
+		void    enableBackgroundPaint(bool mode = true){m_nPaintBackground = mode;}
+		//enable screen saving behind chars, is required for transparent text paint, returns true if mode was changed
+		bool    enableSaveScreen(bool mode = true);
 		bool	setText(const std::string* newText, int max_width = 0, bool force_repaint = true);
 		void 	setTextColor(fb_pixel_t color_text){ m_textColor = color_text;};
 		void	setBackGroundRadius(const int radius, const int type = CORNER_ALL){m_nBgRadius = radius; m_nBgRadiusType = type;};
@@ -207,6 +210,8 @@ class CTextBox
 		inline int	getTextMode()			{return m_nMode;};
 		void paint (void);
 		void hide (void);
+		bool clearScreenBuffer();
+		sigc::signal<void> OnAfterRefresh;
 };
 
 #endif // !defined(AFX_TEXTBOX_H__208DED01_ABEC_491C_A632_5B21057DC5D8__INCLUDED_)