CComponentsForm/CComponentsWindow: add page scroll handling

This provides page scroll with up/down, left/right or combined.
Usage of exec() methods with implemented signals allows a
generic implematation of button or other message handling with
signal/slot solutions.

still to do: page cache

src/gui/components/cc_frm_window.h

@@ -110,6 +110,9 @@ class CComponentsWindow : public CComponentsForm
 		///initialize position
 		void initWindowPos();
 
+		///returns true, if current page is changed, see also: setCurrentPage()
+		bool isPageChanged();
+
 	public:
 		enum
 		{
@@ -192,6 +195,9 @@ class CComponentsWindow : public CComponentsForm
 		void paintCurPage(bool do_save_bg = CC_SAVE_SCREEN_NO);
 		///paint defined page of body, parameter number 0...n
 		void paintPage(const u_int8_t& page_number, bool do_save_bg = CC_SAVE_SCREEN_NO);
+		///enable/disable page scroll, parameter1 default enabled for up/down keys, only for body!
+		void enablePageScroll(const int& mode = PG_SCROLL_M_UP_DOWN_KEY);
+
 		///set width of body scrollbar
 		void setScrollBarWidth(const int& scrollbar_width);