diff --git a/ChangeLog.txt b/ChangeLog.txt
index 8cd44db6aa..75b5f749d3 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -10,6 +10,32 @@
      * Change, ! Fix, % Optimization, + Addition, - Removal, ; Comment
  */
 
+2013-05-10 08:28 UTC+0200 Przemyslaw Czerpak (druzus/at/poczta.onet.pl)
+  * include/hbgtinfo.ch
+    + added HB_GTI_REDRAWMAX
+      It sets maximum number of unchanged neighboring chars in redrawn
+      line. It may help to optimize screen updates in some GTs.
+
+  * include/hbgtcore.h
+  * src/rtl/hbgtcore.c
+  * contrib/hbct/ctwin.c
+    + respect HB_GTI_REDRAWMAX in default REDRAWDIFF() GT methods.
+
+  * contrib/gtqtc/gtqtc1.cpp
+    ! added protection against font resizing for degenerated console
+      window size.
+    % set HB_GTI_REDRAWMAX to 1
+
+  * src/rtl/gtwvt/gtwvt.c
+    ! translate screen base mouse wheel cords to window based ones.
+    % set HB_GTI_REDRAWMAX to 1
+
+  * src/rtl/gttrm/gttrm.c
+    % set HB_GTI_REDRAWMAX to 8
+
+  * src/rtl/gtwin/gtwin.c
+    % set HB_GTI_REDRAWMAX to 4
+
 2013-05-08 09:57 UTC+0200 Przemyslaw Czerpak (druzus/at/poczta.onet.pl)
   * contrib/gtqtc/gtqtc1.cpp
     * minor: removed {}
diff --git a/contrib/gtqtc/gtqtc1.cpp b/contrib/gtqtc/gtqtc1.cpp
index 1e87761462..86c1174e72 100644
--- a/contrib/gtqtc/gtqtc1.cpp
+++ b/contrib/gtqtc/gtqtc1.cpp
@@ -1621,6 +1621,7 @@ static void hb_gt_qtc_Init( PHB_GT pGT, HB_FHANDLE hFilenoStdin, HB_FHANDLE hFil
    /* SUPER GT initialization */
    HB_GTSUPER_INIT( pGT, hFilenoStdin, hFilenoStdout, hFilenoStderr );
    HB_GTSELF_RESIZE( pGT, pQTC->iRows, pQTC->iCols );
+   HB_GTSELF_SETFLAG( pGT, HB_GTI_REDRAWMAX, 1 );
    HB_GTSELF_SEMICOLD( pGT );
 }
 
@@ -2456,6 +2457,10 @@ void QTConsole::setFontSize( int iFH, int iFW )
       if( iWidth != iFW )
       {
          iDec = ( iFW * 100 ) / iWidth;
+         if( iDec < 1 )
+            iDec = 1;
+         else if( iDec >= 4000 )
+            iDec = 3999;
          iDir = iDec;
          do
          {
@@ -2470,15 +2475,17 @@ void QTConsole::setFontSize( int iFH, int iFW )
 
             if( iWidth < iFW )
             {
-               if( iDir <= iDec )
-                  iDec++;
-               else
+               if( iDir > iDec )
                   break;
+               ++iDec;
             }
             else /* iWidth > iFW */
-               iDir = iDec--;
+            {
+               if( --iDec <= iDir )
+                  iDir = iDec + 1;
+            }
          }
-         while( iDec >= ( iDir >> 1 ) && iDec <= ( iDir << 1 ) );
+         while( iDec > ( iDir >> 1 ) && iDec < ( iDir << 1 ) && iDec < 4000 );
       }
    }
 
diff --git a/contrib/hbct/ctwin.c b/contrib/hbct/ctwin.c
index 6654db738d..7bbf57ca75 100644
--- a/contrib/hbct/ctwin.c
+++ b/contrib/hbct/ctwin.c
@@ -2354,8 +2354,9 @@ static void hb_ctw_gt_RedrawDiff( PHB_GT pGT )
       HB_GTSUPER_REDRAWDIFF( pGT );
    else if( pGT->fRefresh )
    {
-      int i, l, r;
+      int i, l, r, s;
       long lIndex;
+      HB_U32 uiValue;
 
       for( i = 0; i < pGT->iHeight; ++i )
       {
@@ -2365,27 +2366,24 @@ static void hb_ctw_gt_RedrawDiff( PHB_GT pGT )
             for( l = 0; l < pGT->iWidth; ++l, ++lIndex )
             {
                if( pGT->prevBuffer[ lIndex ].uiValue !=
-                   hb_ctw_gt_cellValue( pGT, i, l ) )
-                  break;
-            }
-            if( l < pGT->iWidth )
-            {
-               lIndex = ( long ) ( i + 1 ) * pGT->iWidth - 1;
-               for( r = pGT->iWidth - 1; r > l; --r, --lIndex )
+                   ( uiValue = hb_ctw_gt_cellValue( pGT, i, l ) ) )
                {
-                  if( pGT->prevBuffer[ lIndex ].uiValue !=
-                      hb_ctw_gt_cellValue( pGT, i, r ) )
-                     break;
+                  pGT->prevBuffer[ lIndex ].uiValue = uiValue;
+                  s = r = l;
+                  while( ++l < pGT->iWidth )
+                  {
+                     ++lIndex;
+                     if( pGT->prevBuffer[ lIndex ].uiValue !=
+                         ( uiValue = pGT->screenBuffer[ lIndex ].uiValue ) )
+                     {
+                        pGT->prevBuffer[ lIndex ].uiValue = uiValue;
+                        r = l;
+                     }
+                     else if( pGT->iRedrawMax != 0 && l - r >= pGT->iRedrawMax )
+                        break;
+                  }
+                  HB_GTSELF_REDRAW( pGT, i, s, r - s + 1 );
                }
-               HB_GTSELF_REDRAW( pGT, i, l, r - l + 1 );
-               lIndex = ( long ) i * pGT->iWidth + l;
-               do
-               {
-                  pGT->prevBuffer[ lIndex ].uiValue =
-                     hb_ctw_gt_cellValue( pGT, i, l );
-                  ++lIndex;
-               }
-               while( ++l <= r );
             }
             pGT->pLines[ i ] = HB_FALSE;
          }
diff --git a/include/hbgtcore.h b/include/hbgtcore.h
index b1e6f4f46c..1509081d8c 100644
--- a/include/hbgtcore.h
+++ b/include/hbgtcore.h
@@ -290,8 +290,9 @@ typedef struct _HB_GT_BASE
    PHB_SCREENCELL screenBuffer;     /* window foreground (board) current buffer */
    PHB_SCREENCELL prevBuffer;       /* window foreground (board) previous buffer */
 
-   HB_BOOL *      pLines;           /* Touched Window lines */
-   HB_BOOL        fRefresh;         /* Should Window be refreshed */
+   HB_BOOL *      pLines;           /* touched Window lines */
+   HB_BOOL        fRefresh;         /* should Window be refreshed */
+   int            iRedrawMax;       /* maximum number of unchanged neighboring chars in redrawn line */
 
    HB_BOOL        fVgaCell;
    HB_BOOL        fIsColor;
diff --git a/include/hbgtinfo.ch b/include/hbgtinfo.ch
index 0ff7c697f1..d9852d8f8f 100644
--- a/include/hbgtinfo.ch
+++ b/include/hbgtinfo.ch
@@ -149,6 +149,7 @@
 #define HB_GTI_WINHANDLE        69  /* Get console window low level handle */
 #define HB_GTI_MOUSEPOS_XY      70  /* Get mouse position in pixels */
 #define HB_GTI_DISPIMAGE        71  /* Display image with given name */
+#define HB_GTI_REDRAWMAX        72  /* Maximum number of unchanged neighboring chars in redrawn line */
 
 /* Font weights */
 #define HB_GTI_FONTW_THIN       1
diff --git a/src/rtl/gttrm/gttrm.c b/src/rtl/gttrm/gttrm.c
index 13699cce5b..e9fef62a20 100644
--- a/src/rtl/gttrm/gttrm.c
+++ b/src/rtl/gttrm/gttrm.c
@@ -3086,6 +3086,7 @@ static void hb_gt_trm_Init( PHB_GT pGT, HB_FHANDLE hFilenoStdin, HB_FHANDLE hFil
    HB_GTSUPER_INIT( pGT, hFilenoStdin, hFilenoStdout, hFilenoStderr );
    HB_GTSELF_RESIZE( pGT, iRows, iCols );
    HB_GTSELF_SETFLAG( pGT, HB_GTI_COMPATBUFFER, HB_FALSE );
+   HB_GTSELF_SETFLAG( pGT, HB_GTI_REDRAWMAX, 8 );
    HB_GTSELF_SETFLAG( pGT, HB_GTI_STDOUTCON, pTerm->fStdoutTTY );
    HB_GTSELF_SETFLAG( pGT, HB_GTI_STDERRCON, pTerm->fStderrTTY && pTerm->fOutTTY );
    pTerm->Init( pTerm );
diff --git a/src/rtl/gtwin/gtwin.c b/src/rtl/gtwin/gtwin.c
index bdac204ba1..7c2a4bcc66 100644
--- a/src/rtl/gtwin/gtwin.c
+++ b/src/rtl/gtwin/gtwin.c
@@ -971,6 +971,8 @@ static void hb_gt_win_Init( PHB_GT pGT, HB_FHANDLE hFilenoStdin, HB_FHANDLE hFil
    s_bClosable = s_bOldClosable = hb_gt_win_SetCloseButton( HB_FALSE, HB_FALSE );
    s_bResetColors = HB_FALSE;
 
+   HB_GTSELF_SETFLAG( pGT, HB_GTI_REDRAWMAX, 4 );
+
    if( hb_fsIsDevice( hFilenoStdout ) )
       HB_GTSELF_SETFLAG( pGT, HB_GTI_STDOUTCON, HB_TRUE );
    if( hb_fsIsDevice( hFilenoStderr ) )
diff --git a/src/rtl/gtwvt/gtwvt.c b/src/rtl/gtwvt/gtwvt.c
index a34837962d..5e21661f29 100644
--- a/src/rtl/gtwvt/gtwvt.c
+++ b/src/rtl/gtwvt/gtwvt.c
@@ -2176,6 +2176,9 @@ static void hb_gt_wvt_MouseEvent( PHB_GTWVT pWVT, UINT message, WPARAM wParam, L
    xy.x = LOWORD( lParam );
    xy.y = HIWORD( lParam );
 
+   if( message == WM_MOUSEWHEEL )
+      ScreenToClient( pWVT->hWnd, &xy );
+
    colrow = hb_gt_wvt_GetColRowFromXY( pWVT, xy.x, xy.y );
    if( hb_gt_wvt_SetMousePos( pWVT, colrow.y, colrow.x ) )
       hb_gt_wvt_AddCharToInputQueue( pWVT,
@@ -3184,6 +3187,7 @@ static void hb_gt_wvt_Init( PHB_GT pGT, HB_FHANDLE hFilenoStdin, HB_FHANDLE hFil
    /* SUPER GT initialization */
    HB_GTSUPER_INIT( pGT, hFilenoStdin, hFilenoStdout, hFilenoStderr );
    HB_GTSELF_RESIZE( pGT, pWVT->ROWS, pWVT->COLS );
+   HB_GTSELF_SETFLAG( pGT, HB_GTI_REDRAWMAX, 1 );
    HB_GTSELF_SEMICOLD( pGT );
 
    /* hb_gt_wvt_CreateConsoleWindow( pWVT ); */
diff --git a/src/rtl/hbgtcore.c b/src/rtl/hbgtcore.c
index 28cf6fd1b6..84e2f71551 100644
--- a/src/rtl/hbgtcore.c
+++ b/src/rtl/hbgtcore.c
@@ -1808,6 +1808,12 @@ static HB_BOOL hb_gt_def_Info( PHB_GT pGT, int iType, PHB_GT_INFO pInfo )
             pGT->fVgaCell = hb_itemGetL( pInfo->pNewVal );
          break;
 
+      case HB_GTI_REDRAWMAX:
+         pInfo->pResult = hb_itemPutNI( pInfo->pResult, pGT->iRedrawMax );
+         if( hb_itemType( pInfo->pNewVal ) & HB_IT_NUMERIC )
+            pGT->iRedrawMax = hb_itemGetNI( pInfo->pNewVal );
+         break;
+
       case HB_GTI_BOXCP:
          pInfo->pResult = hb_itemPutC( pInfo->pResult,
                                        pGT->cdpBox ? pGT->cdpBox->id : NULL );
@@ -2329,6 +2335,11 @@ static int hb_gt_def_SetFlag( PHB_GT pGT, int iType, int iNewValue )
          iPrevValue = pGT->fStdErrCon;
          pGT->fStdErrCon = iNewValue != 0;
          break;
+
+      case HB_GTI_REDRAWMAX:
+         iPrevValue = pGT->iRedrawMax;
+         pGT->iRedrawMax = iNewValue;
+         break;
    }
 
    return iPrevValue;
@@ -2515,7 +2526,7 @@ static void hb_gt_def_RedrawDiff( PHB_GT pGT )
 {
    if( pGT->fRefresh )
    {
-      int i, l, r;
+      int i, l, r, s;
       long lIndex;
 
       for( i = 0; i < pGT->iHeight; ++i )
@@ -2527,26 +2538,25 @@ static void hb_gt_def_RedrawDiff( PHB_GT pGT )
             {
                if( pGT->prevBuffer[ lIndex ].uiValue !=
                    pGT->screenBuffer[ lIndex ].uiValue )
-                  break;
-            }
-            if( l < pGT->iWidth )
-            {
-               lIndex = ( long ) ( i + 1 ) * pGT->iWidth - 1;
-               for( r = pGT->iWidth - 1; r > l; --r, --lIndex )
-               {
-                  if( pGT->prevBuffer[ lIndex ].uiValue !=
-                      pGT->screenBuffer[ lIndex ].uiValue )
-                     break;
-               }
-               HB_GTSELF_REDRAW( pGT, i, l, r - l + 1 );
-               lIndex = ( long ) i * pGT->iWidth + l;
-               do
                {
                   pGT->prevBuffer[ lIndex ].uiValue =
                      pGT->screenBuffer[ lIndex ].uiValue;
-                  ++lIndex;
+                  s = r = l;
+                  while( ++l < pGT->iWidth )
+                  {
+                     ++lIndex;
+                     if( pGT->prevBuffer[ lIndex ].uiValue !=
+                         pGT->screenBuffer[ lIndex ].uiValue )
+                     {
+                        pGT->prevBuffer[ lIndex ].uiValue =
+                           pGT->screenBuffer[ lIndex ].uiValue;
+                        r = l;
+                     }
+                     else if( pGT->iRedrawMax != 0 && l - r >= pGT->iRedrawMax )
+                        break;
+                  }
+                  HB_GTSELF_REDRAW( pGT, i, s, r - s + 1 );
                }
-               while( ++l <= r );
             }
             pGT->pLines[ i ] = HB_FALSE;
          }