Corrected wxRTC IsDefault() implementations

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75052 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/richtext/richtextbuffer.h

@@ -793,6 +793,11 @@ public:
     */
     bool IsValid() const { return HasWidth(); }
 
+    /**
+        True if the border has no attributes set.
+    */
+    bool IsDefault() const { return (m_flags == 0); }
+
     /**
         Set the valid flag for this border.
     */
@@ -906,7 +911,7 @@ public:
     void CollectCommonAttributes(const wxTextAttrBorders& attr, wxTextAttrBorders& clashingAttr, wxTextAttrBorders& absentAttr);
 
     /**
-        Returns @true if all borders are valid.
+        Returns @true if at least one border is valid.
     */
     bool IsValid() const { return m_left.IsValid() || m_right.IsValid() || m_top.IsValid() || m_bottom.IsValid(); }