X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/d4a58a7ce50dc06be27dbe5722a6d5761520cb6c..8709d9472bc45411b2123a82a8e6df2da21b3ffa:/src/generic/vscroll.cpp

diff --git a/src/generic/vscroll.cpp b/src/generic/vscroll.cpp
index 96fcd3f54d..0572b8e07b 100644
--- a/src/generic/vscroll.cpp
+++ b/src/generic/vscroll.cpp
@@ -31,6 +31,8 @@
 
 #include "wx/vscroll.h"
 
+#include "wx/utils.h"   // For wxMin/wxMax().
+
 // ============================================================================
 // wxVarScrollHelperEvtHandler declaration
 // ============================================================================
@@ -308,14 +310,17 @@ size_t wxVarScrollHelperBase::GetNewScrollPosition(wxScrollWinEvent& event) cons
     }
     else if ( evtType == wxEVT_SCROLLWIN_PAGEUP )
     {
-        return FindFirstVisibleFromLast(m_unitFirst);
+        // Page up should do at least as much as line up.
+        return wxMin(FindFirstVisibleFromLast(m_unitFirst),
+                    m_unitFirst ? m_unitFirst - 1 : 0);
     }
     else if ( evtType == wxEVT_SCROLLWIN_PAGEDOWN )
     {
+        // And page down should do at least as much as line down.
         if ( GetVisibleEnd() )
-            return GetVisibleEnd() - 1;
+            return wxMax(GetVisibleEnd() - 1, m_unitFirst + 1);
         else
-            return GetVisibleEnd();
+            return wxMax(GetVisibleEnd(), m_unitFirst + 1);
     }
     else if ( evtType == wxEVT_SCROLLWIN_THUMBRELEASE )
     {
@@ -822,7 +827,7 @@ void wxVarHVScrollHelper::RefreshRowColumn(size_t row, size_t column)
         h_rect.x += OnGetColumnWidth(n);
     }
 
-    // refresh but specialize the behavior if we have a single target window
+    // refresh but specialize the behaviour if we have a single target window
     if ( wxVarVScrollHelper::GetTargetWindow() == wxVarHScrollHelper::GetTargetWindow() )
     {
         v_rect.x = h_rect.x;
@@ -889,7 +894,7 @@ void wxVarHVScrollHelper::RefreshRowsColumns(size_t fromRow, size_t toRow,
         h_rect.width += OnGetColumnWidth(nBetween);
     }
 
-    // refresh but specialize the behavior if we have a single target window
+    // refresh but specialize the behaviour if we have a single target window
     if ( wxVarVScrollHelper::GetTargetWindow() == wxVarHScrollHelper::GetTargetWindow() )
     {
         v_rect.x = h_rect.x;