Improve horizontal scrolling in wxRibbonControl.

Scroll by entire "sections", i.e. panes of the ribbon, instead of scrolling by
a fixed number of pixels as it's much more useful and user-friendly to uncover
the next section entirely instead of asking the user to press on the arrow
several times before being able to use it.

Closes #15232.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74068 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/ribbon/page.h

@@ -148,6 +148,7 @@ public:
     
         @see GetMajorAxis()
         @see ScrollPixels()
+        @see ScrollSections()
     */
     virtual bool ScrollLines(int lines);
   
@@ -165,9 +166,27 @@ public:
     
         @see GetMajorAxis()
         @see ScrollLines()
+        @see ScrollSections()
     */
     bool ScrollPixels(int pixels);
 
+    /**
+        Scroll the page by an entire child section.
+
+        The @a sections parameter value should be 1 or -1. This will scroll
+        enough to uncover a partially visible child section or totally uncover
+        the next child section that may not be visible at all.
+
+        @return @true if the page scrolled at least one pixel in the given
+            direction, @false if it did not scroll.
+
+        @see ScrollPixels()
+        @see ScrollSections()
+
+        @since 2.9.5
+    */
+    bool ScrollSections(int sections);
+
     /**
         Get the direction in which ribbon panels are stacked within the page.