From 5abcba0bef1457477d03e938a8ccf5d5d1705f8d Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Mon, 9 Oct 2000 23:25:27 +0000
Subject: [PATCH] drastically reduced scrollbar flicker when thumb is being
 dragged

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/wxUNIVERSAL@8507 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
---
 src/univ/scrolbar.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/univ/scrolbar.cpp b/src/univ/scrolbar.cpp
index bca063c5b2..b53def2ffa 100644
--- a/src/univ/scrolbar.cpp
+++ b/src/univ/scrolbar.cpp
@@ -129,7 +129,8 @@ wxScrollBar::~wxScrollBar()
 
 void wxScrollBar::DoSetThumb(int pos)
 {
-    // don't do checks here, we're a private function
+    // don't assert hecks here, we're a private function which is meant to be
+    // called with any args at all
     if ( pos < 0 )
     {
         pos = 0;
@@ -139,6 +140,12 @@ void wxScrollBar::DoSetThumb(int pos)
         pos = m_range - m_thumbSize;
     }
 
+    if ( m_thumbPos == pos )
+    {
+        // nothing changed, avoid refreshes which would provoke flicker
+        return;
+    }
+
     if ( m_thumbPosOld == -1 )
     {
         // remember the old thumb position