diff --git a/common/base_screen.cpp b/common/base_screen.cpp
index 72132644ed..559bfd7bb8 100644
--- a/common/base_screen.cpp
+++ b/common/base_screen.cpp
@@ -87,13 +87,6 @@ void BASE_SCREEN::InitDatas()
 }
 
 
-/**
- * Get screen units scalar.
- *
- * Default implementation returns scalar used for schematic screen.  The
- * internal units used by the schematic screen is 1 mil (0.001").  Override
- * this in derived classes that require internal units other than 1 mil.
- */
 int BASE_SCREEN::GetInternalUnits( void )
 {
     return EESCHEMA_INTERNAL_UNIT;
@@ -119,23 +112,13 @@ void BASE_SCREEN::SetPageSize( wxSize& aPageSize )
 }
 
 
-/**
- * Function GetScalingFactor
- * @return the the current scale used to draw items on screen
- * draw coordinates are user coordinates * GetScalingFactor( )
- */
 double BASE_SCREEN::GetScalingFactor() const
 {
     double scale = 1.0 / GetZoom();
     return scale;
 }
 
-/**
- * Function SetScalingFactor
- * calculates the .m_Zoom member to have a given scaling factor
- * @param aScale - the the current scale used to draw items on screen
- * draw coordinates are user coordinates * GetScalingFactor()
- */
+
 void BASE_SCREEN::SetScalingFactor(double aScale )
 {
     double zoom = aScale;
@@ -152,6 +135,7 @@ void BASE_SCREEN::SetScalingFactor(double aScale )
     SetZoom( zoom );
 }
 
+
 void BASE_SCREEN::SetZoomList( const wxArrayDouble& zoomlist )
 {
     if( !m_ZoomList.IsEmpty() )
@@ -293,7 +277,6 @@ void BASE_SCREEN::SetGrid( const wxRealPoint& size )
 }
 
 
-/* Set grid size from command ID. */
 void BASE_SCREEN::SetGrid( int id  )
 {
     wxASSERT( !m_grids.empty() );
@@ -462,6 +445,7 @@ wxPoint BASE_SCREEN::GetCrossHairScreenPosition() const
     return pos;
 }
 
+
 void BASE_SCREEN::SetCrossHairPosition( const wxPoint& aPosition, bool aSnapToGrid )
 {
     if( aSnapToGrid )
diff --git a/common/drawframe.cpp b/common/drawframe.cpp
index 8c92cac215..779ef087bd 100644
--- a/common/drawframe.cpp
+++ b/common/drawframe.cpp
@@ -1,10 +1,31 @@
-/*****************/
-/* drawframe.cpp */
-/*****************/
+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2004 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
+ * Copyright (C) 2008-2011 Wayne Stambaugh <stambaughw@verizon.net>
+ * Copyright (C) 2004-2011 KiCad Developers, see change_log.txt for contributors.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
 
-#ifdef __GNUG__
-#pragma implementation
-#endif
+/**
+ * @file drawframe.cpp
+ */
 
 #include "fctsys.h"
 #include "appl_wxstruct.h"
@@ -23,10 +44,11 @@
 #include <wx/fontdlg.h>
 
 
-/* Definitions for enabling and disabling extra debugging output.  Please
- * remember to set these to 0 before committing changes to SVN.
+/**
+ * Definition for enabling and disabling scroll bar setting trace output.  See the
+ * wxWidgets documentation on useing the WXTRACE environment variable.
  */
-#define DEBUG_DUMP_SCROLLBAR_SETTINGS 0   // Set to 1 to print scroll bar settings.
+static const wxString traceScrollSettings( wxT( "KicadScrollSettings" ) );
 
 
 /* Configuration entry names. */
@@ -83,7 +105,7 @@ EDA_DRAW_FRAME::EDA_DRAW_FRAME( wxWindow* father, int idtype, const wxString& ti
     m_Draw_Axis           = FALSE;  // TRUE to draw axis.
     m_Draw_Sheet_Ref      = FALSE;  // TRUE to display reference sheet.
     m_Print_Sheet_Ref     = TRUE;   // TRUE to print reference sheet.
-    m_Draw_Auxiliary_Axis = FALSE;  // TRUE draw auxilary axis.
+    m_Draw_Auxiliary_Axis = FALSE;  // TRUE draw auxiliary axis.
     m_Draw_Grid_Axis      = FALSE;  // TRUE to draw the grid axis
     m_CursorShape         = 0;
     m_LastGridSizeId      = 0;
@@ -253,44 +275,32 @@ void EDA_DRAW_FRAME::OnUpdateCrossHairStyle( wxUpdateUIEvent& aEvent )
 }
 
 
-// Virtual function
 void EDA_DRAW_FRAME::ReCreateAuxiliaryToolbar()
 {
 }
 
 
-// Virtual function
 void EDA_DRAW_FRAME::ReCreateMenuBar()
 {
 }
 
 
-// Virtual function
 void EDA_DRAW_FRAME::OnHotKey( wxDC* aDC, int aHotKey, const wxPoint& aPosition, EDA_ITEM* aItem )
 {
 }
 
 
-// Virtual function
 void EDA_DRAW_FRAME::ToolOnRightClick( wxCommandEvent& event )
 {
 }
 
 
-/**
- * Function PrintPage (virtual)
- * used to print a page
- * this basic function must be derived to be used for printing
- * because EDA_DRAW_FRAME does not know how to print a page
- * This is the reason it is a virtual function
- */
 void EDA_DRAW_FRAME::PrintPage( wxDC* aDC,int aPrintMask, bool aPrintMirrorMode, void* aData )
 {
     wxMessageBox( wxT("EDA_DRAW_FRAME::PrintPage() error") );
 }
 
 
-// Virtual function
 void EDA_DRAW_FRAME::OnSelectGrid( wxCommandEvent& event )
 {
     int* clientData;
@@ -352,14 +362,6 @@ void EDA_DRAW_FRAME::OnSelectGrid( wxCommandEvent& event )
 }
 
 
-/**
- * Set the zoom when selected by the Zoom List Box
- *  Note:
- *      position 0 = Fit in Page
- *      position >= 1 = zoom (1 to zoom max)
- *      last position : special zoom
- *      virtual function
- */
 void EDA_DRAW_FRAME::OnSelectZoom( wxCommandEvent& event )
 {
     if( m_SelZoomBox == NULL )
@@ -388,7 +390,6 @@ void EDA_DRAW_FRAME::OnSelectZoom( wxCommandEvent& event )
 }
 
 
-/* Return the current zoom level */
 double EDA_DRAW_FRAME::GetZoom( void )
 {
     return GetScreen()->GetZoom();
@@ -401,7 +402,6 @@ void EDA_DRAW_FRAME::OnMouseEvent( wxMouseEvent& event )
 }
 
 
-// Virtual
 void EDA_DRAW_FRAME::OnLeftDClick( wxDC* DC, const wxPoint& MousePos )
 {
 }
@@ -413,8 +413,6 @@ void EDA_DRAW_FRAME::DisplayToolMsg( const wxString& msg )
 }
 
 
-/* Display current unit Selection on Statusbar
- */
 void EDA_DRAW_FRAME::DisplayUnitsMsg()
 {
     wxString msg;
@@ -439,8 +437,6 @@ void EDA_DRAW_FRAME::DisplayUnitsMsg()
 
 
 
-/* Recalculate the size of toolbars and display panel.
- */
 void EDA_DRAW_FRAME::OnSize( wxSizeEvent& SizeEv )
 {
     m_FrameSize = GetClientSize( );
@@ -470,10 +466,6 @@ void EDA_DRAW_FRAME::SetToolID( int aId, int aCursor, const wxString& aToolMsg )
 }
 
 
-/*****************************/
-/* default virtual functions */
-/*****************************/
-
 void EDA_DRAW_FRAME::OnGrid( int grid_type )
 {
 }
@@ -517,41 +509,134 @@ bool EDA_DRAW_FRAME::HandleBlockEnd( wxDC* DC )
 void EDA_DRAW_FRAME::AdjustScrollBars( const wxPoint& aCenterPosition )
 {
     int     unitsX, unitsY, posX, posY;
-    wxSize  drawingSize, clientSize;
+    wxSize  clientSize, logicalClientSize, virtualSize;
     BASE_SCREEN* screen = GetScreen();
     bool noRefresh = true;
 
     if( screen == NULL || DrawPanel == NULL )
         return;
 
-    // The drawing size is twice the current page size.
-    drawingSize = screen->ReturnPageSize() * 2;
+    double scalar = screen->GetScalingFactor();
+
+    wxLogTrace( traceScrollSettings, wxT( "Center Position = ( %d, %d ), scalar = %0.5f." ),
+                aCenterPosition.x, aCenterPosition.y, scalar );
 
     // Calculate the portion of the drawing that can be displayed in the
     // client area at the current zoom level.
     clientSize = DrawPanel->GetClientSize();
 
-    double scalar = screen->GetScalingFactor();
-    clientSize.x = wxRound( (double) clientSize.x / scalar );
-    clientSize.y = wxRound( (double) clientSize.y / scalar );
+    // The logical size of the client window.
+    logicalClientSize.x = wxRound( (double) clientSize.x / scalar );
+    logicalClientSize.y = wxRound( (double) clientSize.y / scalar );
 
-    /* Adjust drawing size when zooming way out to prevent centering around
-     * cursor problems. */
-    if( clientSize.x > drawingSize.x || clientSize.y > drawingSize.y )
-        drawingSize = clientSize;
+    // The upper left corner of the drawing in device units.
+    int w = screen->ReturnPageSize().x;
+    int h = screen->ReturnPageSize().y;
 
-    drawingSize.x += wxRound( (double) clientSize.x / 2.0 );
-    drawingSize.y += wxRound( (double) clientSize.y / 2.0 );
+    // The drawing rectangle logical units
+    wxRect drawingRect( wxPoint( 0, 0 ),  wxSize( w, h ) );
 
+    wxLogTrace( traceScrollSettings, wxT( "Logical drawing rect = ( %d, %d, %d, %d )." ),
+                drawingRect.x, drawingRect.y, drawingRect.width, drawingRect.height );
+    wxLogTrace( traceScrollSettings, wxT( "   left %d, right %d, top %d, bottome %d" ),
+                drawingRect.GetLeft(), drawingRect.GetRight(),
+                drawingRect.GetTop(), drawingRect.GetBottom() );
+
+    // The size of the client rectangle in logical units.
+    int x = wxRound( (double) aCenterPosition.x - ( (double) logicalClientSize.x / 2.0 ) );
+    int y = wxRound( (double) aCenterPosition.y - ( (double) logicalClientSize.y / 2.0 ) );
+
+    // If drawn around the center, adjust the client rectangle accordingly.
     if( screen->m_Center )
     {
-        screen->m_DrawOrg.x = -wxRound( (double) drawingSize.x / 2.0 );
-        screen->m_DrawOrg.y = -wxRound( (double) drawingSize.y / 2.0 );
+        x += wxRound( (double) drawingRect.width / 2.0 );
+        y += wxRound( (double) drawingRect.height / 2.0 );
+    }
+
+    wxRect logicalClientRect( wxPoint( x, y ), logicalClientSize );
+
+    wxLogTrace( traceScrollSettings, wxT( "Logical client rect = ( %d, %d, %d, %d )." ),
+                logicalClientRect.x, logicalClientRect.y,
+                logicalClientRect.width, logicalClientRect.height );
+    wxLogTrace( traceScrollSettings, wxT( "   left %d, right %d, top %d, bottome %d" ),
+                logicalClientRect.GetLeft(), logicalClientRect.GetRight(),
+                logicalClientRect.GetTop(), logicalClientRect.GetBottom() );
+
+    if( drawingRect == logicalClientRect )
+    {
+        virtualSize = drawingRect.GetSize();
+    }
+    else if( drawingRect.Contains( logicalClientRect ) )
+    {
+        virtualSize = drawingRect.GetSize();
     }
     else
     {
-        screen->m_DrawOrg.x = -wxRound( (double) clientSize.x / 2.0 );
-        screen->m_DrawOrg.y = -wxRound( (double) clientSize.y / 2.0 );
+        int drawingCenterX = drawingRect.x + ( drawingRect.width / 2 );
+        int clientCenterX = logicalClientRect.x + ( logicalClientRect.width / 2 );
+        int drawingCenterY = drawingRect.y + ( drawingRect.height / 2 );
+        int clientCenterY = logicalClientRect.y + ( logicalClientRect.height / 2 );
+
+        if( logicalClientRect.width > drawingRect.width )
+        {
+            if( drawingCenterX > clientCenterX )
+                virtualSize.x = ( drawingCenterX - logicalClientRect.GetLeft() ) * 2;
+            else if( drawingCenterX < clientCenterX )
+                virtualSize.x = ( logicalClientRect.GetRight() - drawingCenterX ) * 2;
+            else
+                virtualSize.x = logicalClientRect.width;
+        }
+        else if( logicalClientRect.width < drawingRect.width )
+        {
+            if( drawingCenterX > clientCenterX )
+                virtualSize.x = drawingRect.width +
+                                ( (drawingRect.GetLeft() - logicalClientRect.GetLeft() ) * 2 );
+            else if( drawingCenterX < clientCenterX )
+                virtualSize.x = drawingRect.width +
+                                ( (logicalClientRect.GetRight() - drawingRect.GetRight() ) * 2 );
+            else
+                virtualSize.x = drawingRect.width;
+        }
+        else
+        {
+            virtualSize.x = drawingRect.width;
+        }
+
+        if( logicalClientRect.height > drawingRect.height )
+        {
+            if( drawingCenterY > clientCenterY )
+                virtualSize.y = ( drawingCenterY - logicalClientRect.GetTop() ) * 2;
+            else if( drawingCenterY < clientCenterY )
+                virtualSize.y = ( logicalClientRect.GetBottom() - drawingCenterY ) * 2;
+            else
+                virtualSize.y = logicalClientRect.height;
+        }
+        else if( logicalClientRect.height < drawingRect.height )
+        {
+            if( drawingCenterY > clientCenterY )
+                virtualSize.y = drawingRect.height +
+                                ( ( drawingRect.GetTop() - logicalClientRect.GetTop() ) * 2 );
+            else if( drawingCenterY < clientCenterY )
+                virtualSize.y = drawingRect.height +
+                                ( ( logicalClientRect.GetBottom() - drawingRect.GetBottom() ) * 2 );
+            else
+                virtualSize.y = drawingRect.height;
+        }
+        else
+        {
+            virtualSize.y = drawingRect.height;
+        }
+    }
+
+    if( screen->m_Center )
+    {
+        screen->m_DrawOrg.x = -( wxRound( (double) virtualSize.x / 2.0 ) );
+        screen->m_DrawOrg.y = -( wxRound( (double) virtualSize.y / 2.0 ) );
+    }
+    else
+    {
+        screen->m_DrawOrg.x = -( wxRound( (double) (virtualSize.x - drawingRect.width) / 2.0 ) );
+        screen->m_DrawOrg.y = -( wxRound( (double) (virtualSize.y - drawingRect.height) / 2.0 ) );
     }
 
     /* Always set scrollbar pixels per unit to 1 unless you want the zoom
@@ -562,36 +647,57 @@ void EDA_DRAW_FRAME::AdjustScrollBars( const wxPoint& aCenterPosition )
      */
     screen->m_ScrollPixelsPerUnitX = screen->m_ScrollPixelsPerUnitY = 1;
 
-    // Calculate the number of scroll bar units for the given zoom level. */
-    unitsX = wxRound( (double) drawingSize.x * scalar );
-    unitsY = wxRound( (double) drawingSize.y * scalar );
+    // Calculate the number of scroll bar units for the given zoom level in device units.
+    unitsX = wxRound( (double) virtualSize.x * scalar );
+    unitsY = wxRound( (double) virtualSize.y * scalar );
 
-    // Calculate the position, place the cursor at the center of screen.
+    // Calculate the scroll bar position in logical units to place the center position at
+    // the center of client rectangle.
     screen->SetScrollCenterPosition( aCenterPosition );
-    posX = aCenterPosition.x - screen->m_DrawOrg.x;
-    posY = aCenterPosition.y - screen->m_DrawOrg.y;
-
-    posX -= wxRound( (double) clientSize.x / 2.0 );
-    posY -= wxRound( (double) clientSize.y / 2.0 );
-
-    if( posX < 0 )
-        posX = 0;
-
-    if( posY < 0 )
-        posY = 0;
+    posX = aCenterPosition.x - wxRound( (double) logicalClientRect.width / 2.0 ) -
+           screen->m_DrawOrg.x;
+    posY = aCenterPosition.y - wxRound( (double) logicalClientRect.height / 2.0 ) -
+           screen->m_DrawOrg.y;
 
+    // Convert scroll bar position to device units.
     posX = wxRound( (double) posX * scalar );
     posY = wxRound( (double) posY * scalar );
 
+    if( posX < 0 )
+    {
+        wxLogTrace( traceScrollSettings, wxT( "Required scroll bar X position %d" ), posX );
+        posX = 0;
+    }
+
+    if( posX > unitsX )
+    {
+        wxLogTrace( traceScrollSettings, wxT( "Required scroll bar X position %d" ), posX );
+        posX = unitsX;
+    }
+
+    if( posY < 0 )
+    {
+        wxLogTrace( traceScrollSettings, wxT( "Required scroll bar Y position %d" ), posY );
+        posY = 0;
+    }
+
+    if( posY > unitsY )
+    {
+        wxLogTrace( traceScrollSettings, wxT( "Required scroll bar Y position %d" ), posY );
+        posY = unitsY;
+    }
+
     screen->m_ScrollbarPos = wxPoint( posX, posY );
     screen->m_ScrollbarNumber = wxSize( unitsX, unitsY );
 
-#if DEBUG_DUMP_SCROLLBAR_SETTINGS
-    wxLogDebug( wxT( "SetScrollbars(%d, %d, %d, %d, %d, %d)" ),
+    wxLogTrace( traceScrollSettings,
+                wxT( "Drawing = (%d, %d), Client = (%d, %d), Offset = (%d, %d), \
+SetScrollbars(%d, %d, %d, %d, %d, %d)" ),
+                virtualSize.x, virtualSize.y, logicalClientSize.x, logicalClientSize.y,
+                screen->m_DrawOrg.x, screen->m_DrawOrg.y,
                 screen->m_ScrollPixelsPerUnitX, screen->m_ScrollPixelsPerUnitY,
                 screen->m_ScrollbarNumber.x, screen->m_ScrollbarNumber.y,
                 screen->m_ScrollbarPos.x, screen->m_ScrollbarPos.y );
-#endif
 
     DrawPanel->SetScrollbars( screen->m_ScrollPixelsPerUnitX,
                               screen->m_ScrollPixelsPerUnitY,
@@ -602,11 +708,6 @@ void EDA_DRAW_FRAME::AdjustScrollBars( const wxPoint& aCenterPosition )
 }
 
 
-/**
- * Function SetLanguage
- * called on a language menu selection
- * when using a derived function, do not forget to call this one
- */
 void EDA_DRAW_FRAME::SetLanguage( wxCommandEvent& event )
 {
     EDA_BASE_FRAME::SetLanguage( event );
@@ -644,15 +745,6 @@ double RoundTo0( double x, double precision )
 }
 
 
-/**
- * Function UpdateStatusBar
- * Displays in the bottom of the main window a stust:
- *  - Absolute Cursor coordinates
- *  - Relative Cursor coordinates (relative to the last coordinate stored
- *     when actiavte the space bar)
- * ( in this status is also displayed the zoom level, but this is not made
- *   by this function )
- */
 void EDA_DRAW_FRAME::UpdateStatusBar()
 {
     wxString        Line;
@@ -740,12 +832,6 @@ void EDA_DRAW_FRAME::UpdateStatusBar()
 }
 
 
-/**
- * Load draw frame specific configuration settings.
- *
- * Don't forget to call this base method from any derived classes or the
- * settings will not get loaded.
- */
 void EDA_DRAW_FRAME::LoadSettings()
 {
     wxASSERT( wxGetApp().m_EDA_Config != NULL );
@@ -768,12 +854,6 @@ void EDA_DRAW_FRAME::LoadSettings()
 }
 
 
-/**
- * Save draw frame specific configuration settings.
- *
- * Don't forget to call this base method from any derived classes or the
- * settings will not get saved.
- */
 void EDA_DRAW_FRAME::SaveSettings()
 {
     wxASSERT( wxGetApp().m_EDA_Config != NULL );
diff --git a/common/drawpanel.cpp b/common/drawpanel.cpp
index 61db33efaa..0d40e02564 100644
--- a/common/drawpanel.cpp
+++ b/common/drawpanel.cpp
@@ -1162,7 +1162,24 @@ void EDA_DRAW_PANEL::OnKeyEvent( wxKeyEvent& event )
     GetParent()->GeneralControl( &DC, pos, localkey );
 
 #ifdef __WINDOWS__
-    event.Skip();   // Allow menu shortcut processing on Windows.
+    // Disable the default scrolling command keys which break KiCad's zooming and
+    // panning.  This is also likely the reason skip was disabled for other platforms.
+    // There probably needs to be some more investigation done here.
+    switch( event.GetKeyCode() )
+    {
+    case WXK_HOME:
+    case WXK_END:
+    case WXK_PAGEUP:
+    case WXK_PAGEDOWN:
+    case WXK_UP:
+    case WXK_DOWN:
+    case WXK_LEFT:
+    case WXK_RIGHT:
+        break;
+
+    default:
+        event.Skip();   // Allow menu shortcut processing on Windows.
+    }
 #endif
 }
 
diff --git a/eeschema/viewlib_frame.cpp b/eeschema/viewlib_frame.cpp
index 46202138b4..05f2d389bb 100644
--- a/eeschema/viewlib_frame.cpp
+++ b/eeschema/viewlib_frame.cpp
@@ -1,3 +1,28 @@
+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2004 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
+ * Copyright (C) 2008-2011 Wayne Stambaugh <stambaughw@verizon.net>
+ * Copyright (C) 2004-2011 KiCad Developers, see change_log.txt for contributors.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
 /**
  * @file viewlib_frame.cpp
  */
@@ -24,13 +49,11 @@ wxString LIB_VIEW_FRAME::m_entryName;
 int LIB_VIEW_FRAME::m_unit = 1;
 int LIB_VIEW_FRAME::m_convert = 1;
 
-// When the viewer is used to select a component in schematic, the selected component is here.
+
+/// When the viewer is used to select a component in schematic, the selected component is here.
 wxString LIB_VIEW_FRAME::m_exportToEeschemaCmpName;
 
 
-/*****************************/
-/* class WinEDA_ViewlibFrame */
-/*****************************/
 BEGIN_EVENT_TABLE( LIB_VIEW_FRAME, EDA_DRAW_FRAME )
     /* Window events */
     EVT_CLOSE( LIB_VIEW_FRAME::OnCloseWindow )
@@ -212,8 +235,8 @@ LIB_VIEW_FRAME::LIB_VIEW_FRAME( wxWindow* father, CMP_LIBRARY* Library, wxSemaph
                       wxAuiPaneInfo( mesg ).Name( wxT( "MsgPanel" ) ).Bottom().Layer(10) );
 
     /* Now the minimum windows are fixed, set library list
-    and component list of the previous values from last viewlib use
-    */
+     * and component list of the previous values from last viewlib use
+     */
     if( m_LibListWindow )
     {
         wxAuiPaneInfo& pane = m_auimgr.GetPane(m_LibListWindow);
@@ -253,15 +276,13 @@ void LIB_VIEW_FRAME::OnCloseWindow( wxCloseEvent& Event )
         // This window will be destroyed by the calling function,
         // to avoid side effects
     }
-
     else
+    {
         Destroy();
+    }
 }
 
 
-/*
- * Resize sub windows when dragging a sash window border
- */
 void LIB_VIEW_FRAME::OnSashDrag( wxSashEvent& event )
 {
     if( event.GetDragStatus() == wxSASH_STATUS_OUT_OF_RANGE )
@@ -340,9 +361,9 @@ double LIB_VIEW_FRAME::BestZoom()
     // Reserve a 10% margin around component bounding box.
     double margin_scale_factor = 0.8;
     double zx =(double) BoundaryBox.GetWidth() /
-                    ( margin_scale_factor * (double)size.x );
+               ( margin_scale_factor * (double)size.x );
     double zy = (double) BoundaryBox.GetHeight() /
-                    ( margin_scale_factor * (double)size.y);
+                ( margin_scale_factor * (double)size.y);
 
     // Calculates the best zoom
     bestzoom = MAX( zx, zy );
@@ -358,12 +379,6 @@ double LIB_VIEW_FRAME::BestZoom()
 }
 
 
-/**
- * Function ReCreateListLib
- *
- * Creates or recreates the list of current loaded libraries.
- * This list is sorted, with the library cache always at end of the list
- */
 void LIB_VIEW_FRAME::ReCreateListLib()
 {
     if( m_LibList == NULL )
@@ -475,10 +490,6 @@ void LIB_VIEW_FRAME::ClickOnCmpList( wxCommandEvent& event )
 }
 
 
-
-/*
- * Export the current component to schematic and close the library browser
- */
 void LIB_VIEW_FRAME::ExportToSchematicLibraryPart( wxCommandEvent& event )
 {
     int ii = m_CmpList->GetSelection();
@@ -496,12 +507,6 @@ void LIB_VIEW_FRAME::ExportToSchematicLibraryPart( wxCommandEvent& event )
 #define CMPLIST_WIDTH_KEY wxT( "Cmplist_width" )
 
 
-/**
- * Load library viewer frame specific configuration settings.
- *
- * Don't forget to call this base method from any derived classes or the
- * settings will not get loaded.
- */
 void LIB_VIEW_FRAME::LoadSettings( )
 {
     wxConfig* cfg ;
@@ -526,12 +531,6 @@ void LIB_VIEW_FRAME::LoadSettings( )
 }
 
 
-/**
- * Save library viewer frame specific configuration settings.
- *
- * Don't forget to call this base method from any derived classes or the
- * settings will not get saved.
- */
 void LIB_VIEW_FRAME::SaveSettings()
 {
     wxConfig* cfg;
@@ -547,9 +546,7 @@ void LIB_VIEW_FRAME::SaveSettings()
     cfg->Write( CMPLIST_WIDTH_KEY, m_CmpListSize.x );
 }
 
-/** Called on activate the frame.
- * Reload the libraries lists that can be changed by the schematic editor or the library editor
- */
+
 void LIB_VIEW_FRAME::OnActivate( wxActivateEvent& event )
 {
     EDA_DRAW_FRAME::OnActivate( event );
diff --git a/eeschema/viewlib_frame.h b/eeschema/viewlib_frame.h
index 08e0868902..4520df1952 100644
--- a/eeschema/viewlib_frame.h
+++ b/eeschema/viewlib_frame.h
@@ -1,3 +1,32 @@
+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2004 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
+ * Copyright (C) 2008-2011 Wayne Stambaugh <stambaughw@verizon.net>
+ * Copyright (C) 2004-2011 KiCad Developers, see change_log.txt for contributors.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+/**
+ * @file viewlib_frame.h
+ */
+
 #ifndef __LIBVIEWFRM_H__
 #define __LIBVIEWFRM_H__
 
@@ -50,8 +79,22 @@ public:
     ~LIB_VIEW_FRAME();
 
     void OnSize( wxSizeEvent& event );
+
+    /**
+     * Function OnSashDrag
+     * resizes the child windows when dragging a sash window border.
+     */
+
     void OnSashDrag( wxSashEvent& event );
+
+    /**
+     * Function ReCreateListLib
+     *
+     * Creates or recreates the list of current loaded libraries.
+     * This list is sorted, with the library cache always at end of the list
+     */
     void ReCreateListLib();
+
     void ReCreateListCmp();
     void Process_Special_Functions( wxCommandEvent& event );
     void DisplayLibInfos();
@@ -69,7 +112,22 @@ public:
 
     void GeneralControl( wxDC* aDC, const wxPoint& aPosition, int aHotKey = 0 );
 
+    /**
+     * Function LoadSettings
+     * loads the library viewer frame specific configuration settings.
+     *
+     * Don't forget to call this base method from any derived classes or the
+     * settings will not get loaded.
+     */
     void LoadSettings();
+
+    /**
+     * Function SaveSettings
+     * save library viewer frame specific configuration settings.
+     *
+     * Don't forget to call this base method from any derived classes or the
+     * settings will not get saved.
+     */
     void SaveSettings();
 
     wxString& GetEntryName( void ) const { return m_entryName; }
@@ -79,12 +137,20 @@ public:
     int  GetConvert( void ) { return m_convert; }
 
 private:
-    /** OnActivate event funtion( virtual )
+    /**
+     * Function OnActivate
+     * is called when the frame frame is activate to reload the libraries and component lists
+     * that can be changed by the schematic editor or the library editor.
      */
-    virtual void     OnActivate( wxActivateEvent& event );
+    virtual void OnActivate( wxActivateEvent& event );
 
     void SelectCurrentLibrary();
     void SelectAndViewLibraryPart( int option );
+
+    /**
+     * Function ExportToSchematicLibraryPart
+     * exports the current component to schematic and close the library browser.
+     */
     void ExportToSchematicLibraryPart( wxCommandEvent& event );
     void ViewOneLibraryContent( CMP_LIBRARY* Lib, int Flag );
     bool OnRightClick( const wxPoint& MousePos, wxMenu* PopMenu );
diff --git a/include/class_base_screen.h b/include/class_base_screen.h
index 08b07c8f19..7b94c53d25 100644
--- a/include/class_base_screen.h
+++ b/include/class_base_screen.h
@@ -171,15 +171,24 @@ public:
 
     virtual void SetDrawItems( EDA_ITEM* aItem ) { m_drawList = aItem; }
 
-    void         InitDatas();
+    void InitDatas();
 
-    void         SetFileName( const wxString& aFileName ) { m_fileName = aFileName; }
+    void SetFileName( const wxString& aFileName ) { m_fileName = aFileName; }
 
-    wxString     GetFileName() const { return m_fileName; }
+    wxString GetFileName() const { return m_fileName; }
 
-    void         SetPageSize( wxSize& aPageSize );
-    wxSize       ReturnPageSize( void );
-    virtual int  GetInternalUnits( void );
+    void SetPageSize( wxSize& aPageSize );
+    wxSize ReturnPageSize( void );
+
+    /**
+     * Function GetInternalUnits
+     * @return the screen units scalar.
+     *
+     * Default implementation returns scalar used for schematic screen.  The
+     * internal units used by the schematic screen is 1 mil (0.001").  Override
+     * this in derived classes that require internal units other than 1 mil.
+     */
+    virtual int GetInternalUnits( void );
 
     /**
      * Function GetCrossHairPosition
@@ -227,7 +236,7 @@ public:
      * picked items are deleted by ClearUndoORRedoList() according to their
      * status
      */
-    virtual void               ClearUndoRedoList();
+    virtual void ClearUndoRedoList();
 
     /**
      * Function PushCommandToUndoList
@@ -236,7 +245,7 @@ public:
      * reached
      * ( using ClearUndoORRedoList)
      */
-    virtual void               PushCommandToUndoList( PICKED_ITEMS_LIST* aItem );
+    virtual void PushCommandToUndoList( PICKED_ITEMS_LIST* aItem );
 
     /**
      * Function PushCommandToRedoList
@@ -245,7 +254,7 @@ public:
      * reached
      * ( using ClearUndoORRedoList)
      */
-    virtual void               PushCommandToRedoList( PICKED_ITEMS_LIST* aItem );
+    virtual void PushCommandToRedoList( PICKED_ITEMS_LIST* aItem );
 
     /** PopCommandFromUndoList
      * return the last command to undo and remove it from list
@@ -271,12 +280,12 @@ public:
     }
 
 
-    void    SetModify() { m_FlagModified = true; }
-    void    ClrModify() { m_FlagModified = false;; }
-    void    SetSave() { m_FlagSave = true; }
-    void    ClrSave() { m_FlagSave = false; }
-    int     IsModify() { return m_FlagModified;  }
-    int     IsSave() { return m_FlagSave;  }
+    void SetModify() { m_FlagModified = true; }
+    void ClrModify() { m_FlagModified = false;; }
+    void SetSave() { m_FlagSave = true; }
+    void ClrSave() { m_FlagSave = false; }
+    int IsModify() { return m_FlagModified;  }
+    int IsSave() { return m_FlagSave;  }
 
 
     //----<zoom stuff>---------------------------------------------------------
@@ -284,16 +293,16 @@ public:
     /**
      * Function GetScalingFactor
      * @return the the current scale used to draw items on screen
-     * draw coordinates are user coordinates * GetScalingFactor( )
+     * draw coordinates are user coordinates * GetScalingFactor()
      */
-    double  GetScalingFactor() const;
+    double GetScalingFactor() const;
 
     /**
      * Function SetScalingFactor
      * @param aScale = the the current scale used to draw items on screen
-     * draw coordinates are user coordinates * GetScalingFactor( )
+     * draw coordinates are user coordinates * GetScalingFactor()
      */
-    void        SetScalingFactor( double aScale );
+    void SetScalingFactor( double aScale );
 
     /**
      * Function GetZoom
@@ -301,26 +310,26 @@ public:
      * Note: the zoom factor is NOT the scaling factor
      *       the scaling factor is m_ZoomScalar * GetZoom()
      */
-    double      GetZoom() const;
+    double GetZoom() const;
 
     /**
      * Function SetZoom
      * adjusts the current zoom factor
      * @param coeff - Zoom coefficient.
      */
-    bool        SetZoom( double coeff );
+    bool SetZoom( double coeff );
 
     /**
      * Function SetZoomList
      * sets the list of zoom factors.
      * @param aZoomList An array of zoom factors in ascending order, zero terminated
      */
-    void        SetZoomList( const wxArrayDouble& aZoomList );
+    void SetZoomList( const wxArrayDouble& aZoomList );
 
-    bool        SetNextZoom();
-    bool        SetPreviousZoom();
-    bool        SetFirstZoom();
-    bool        SetLastZoom();
+    bool SetNextZoom();
+    bool SetPreviousZoom();
+    bool SetFirstZoom();
+    bool SetLastZoom();
 
     //----<grid stuff>----------------------------------------------------------
 
@@ -329,7 +338,7 @@ public:
      *
      * @return int - Currently selected grid command ID.
      */
-    int         GetGridId();
+    int GetGridId();
 
     /**
      * Return the grid size of the currently selected grid.
@@ -343,15 +352,20 @@ public:
      *
      * @return GRID_TYPE - The currently selected grid.
      */
-    GRID_TYPE   GetGrid();
+    GRID_TYPE GetGrid();
 
     const wxPoint& GetGridOrigin();
-    void        SetGrid( const wxRealPoint& size );
-    void        SetGrid( int id );
-    void        SetGridList( GRIDS& sizelist );
-    void        AddGrid( const GRID_TYPE& grid );
-    void        AddGrid( const wxRealPoint& size, int id );
-    void        AddGrid( const wxRealPoint& size, EDA_UNITS_T aUnit, int id );
+    void SetGrid( const wxRealPoint& size );
+
+    /**
+     * Function SetGrid
+     * sets the grid size from command ID.
+     */
+    void SetGrid( int id );
+    void SetGridList( GRIDS& sizelist );
+    void AddGrid( const GRID_TYPE& grid );
+    void AddGrid( const wxRealPoint& size, int id );
+    void AddGrid( const wxRealPoint& size, EDA_UNITS_T aUnit, int id );
 
     /**
      * Function GetGridCount().
@@ -359,7 +373,7 @@ public:
      *
      * @returns - The size of the grid list.
      */
-    size_t      GetGridCount() const { return m_grids.size(); }
+    size_t GetGridCount() const { return m_grids.size(); }
 
     /**
      * Function GetGrid()
@@ -368,7 +382,7 @@ public:
      * @param aIndex - The grid list index.
      * @return - The grid object at \a aIndex or the current grid if the grid list is empty.
      */
-    GRID_TYPE&  GetGrid( size_t aIndex );
+    GRID_TYPE& GetGrid( size_t aIndex );
 
     /**
      * Function GetGrids().
@@ -376,7 +390,7 @@ public:
      *
      * @param aList - List to copy to.
      */
-    void         GetGrids( GRIDS& aList );
+    void GetGrids( GRIDS& aList );
 
     void SetMousePosition( const wxPoint& aPosition ) { m_MousePosition = aPosition; }
 
diff --git a/include/wxBasePcbFrame.h b/include/wxBasePcbFrame.h
index 474f3a8a8d..49bea22417 100644
--- a/include/wxBasePcbFrame.h
+++ b/include/wxBasePcbFrame.h
@@ -1,3 +1,28 @@
+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2004 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
+ * Copyright (C) 2008-2011 Wayne Stambaugh <stambaughw@verizon.net>
+ * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
 /**
  * @file wxBasePcbFrame.h
  * @brief Classes used in Pcbnew, CvPcb and GerbView.
@@ -100,6 +125,11 @@ public:
         return (PCB_SCREEN*) EDA_DRAW_FRAME::GetScreen();
     }
 
+    /**
+     * Function BestZoom
+     * @return the "best" zoom to show the entire board or footprint on the screen.
+     */
+
     virtual double BestZoom();
 
     virtual void Show3D_Frame( wxCommandEvent& event );
diff --git a/include/wxstruct.h b/include/wxstruct.h
index 75a960d5e2..f3de177ead 100644
--- a/include/wxstruct.h
+++ b/include/wxstruct.h
@@ -557,6 +557,14 @@ public:
      *                grid size combobox on the toolbar.
      */
     virtual void OnSelectGrid( wxCommandEvent& event );
+
+    /**
+     * Functions OnSelectZoom
+     * sets the zoom factor when selected by the zoom list box in the main tool bar.
+     * @note List position 0 is fit to page
+     *       List position >= 1 = zoom (1 to zoom max)
+     *       Last list position is custom zoom not in zoom list.
+     */
     virtual void OnSelectZoom( wxCommandEvent& event );
 
     // Command event handlers shared by all applications derived from EDA_DRAW_FRAME.
@@ -585,7 +593,12 @@ public:
      */
     virtual void GeneralControl( wxDC* aDC, const wxPoint& aPosition, int aHotKey = 0 ) { }
 
+    /**
+     * Function OnSize
+     * recalculates the size of toolbars and display panel when the frame size changes.
+     */
     virtual void OnSize( wxSizeEvent& event );
+
     void OnEraseBackground( wxEraseEvent& SizeEvent );
 
     virtual void OnZoom( wxCommandEvent& event );
@@ -608,7 +621,10 @@ public:
     /* Return the zoom level which displays the full page on screen */
     virtual double BestZoom() = 0;
 
-    /* Return the current zoom level */
+    /**
+     * Function GetZoom
+     * @return The current zoom level.
+     */
     double GetZoom( void );
 
     void TraceWorkSheet( wxDC* DC, BASE_SCREEN* screen, int line_width );
@@ -655,6 +671,10 @@ public:
      */
     virtual void UpdateStatusBar();
 
+    /**
+     * Function DisplayUnitsMsg
+     * displays current unit pane on the status bar.
+     */
     void DisplayUnitsMsg();
 
     /* Handlers for block commands */
@@ -698,7 +718,22 @@ public:
     void OnSockRequest( wxSocketEvent& evt );
     void OnSockRequestServer( wxSocketEvent& evt );
 
+    /**
+     * Function LoadSettings
+     * loads the draw frame specific configuration settings.
+     *
+     * Don't forget to call this base method from any derived classes or the
+     * settings common to the draw frame will not get loaded.
+     */
     virtual void LoadSettings();
+
+    /**
+     * Funxtion SaveSettings
+     * saves the draw frame specific configuration settings.
+     *
+     * Don't forget to call this base method from any derived classes or the
+     * settings common to the draw frame will not get saved.
+     */
     virtual void SaveSettings();
 
     /**
@@ -1056,7 +1091,7 @@ static inline void AddMenuItem( wxMenu*         aMenu,
  * Each panel has rows, starting at 0. Each row has positions starting at 0. Each item in a panel
  * can have it's row and position set.
  *
- * Eventually panels will be moveable. Each initialization function sets up the panel for this,
+ * Eventually panels will be movable. Each initialization function sets up the panel for this,
  * then after a //==// break has additional calls to anchor toolbars in a way that matches
  * present functionality.
  */
@@ -1076,7 +1111,7 @@ public:
         CloseButton( false );
         LeftDockable( false );
         RightDockable( false );
-        //====================  Remove calls below here for moveable toolbars //
+        //====================  Remove calls below here for movable toolbars //
         Gripper( false );
         DockFixed( true );
         Movable( false );
@@ -1094,7 +1129,7 @@ public:
         CloseButton( false );
         TopDockable( false );
         BottomDockable( false );
-        //====================  Remove calls below here for moveable toolbars //
+        //====================  Remove calls below here for movable toolbars //
         Gripper( false );
         DockFixed( true );
         Movable( false );
diff --git a/pcbnew/basepcbframe.cpp b/pcbnew/basepcbframe.cpp
index 212b680a06..ba86c83c08 100644
--- a/pcbnew/basepcbframe.cpp
+++ b/pcbnew/basepcbframe.cpp
@@ -122,9 +122,6 @@ void PCB_BASE_FRAME::SetBoard( BOARD* aBoard )
 }
 
 
-/**
- * Return the "best" zoom, i.e. the zoom which shows the entire board on screen
- */
 double PCB_BASE_FRAME::BestZoom( void )
 {
     int    dx, dy;
@@ -151,6 +148,7 @@ double PCB_BASE_FRAME::BestZoom( void )
         jj = 32.0;
 
     double bestzoom = MAX( ii, jj );
+
     GetScreen()->SetScrollCenterPosition( m_Pcb->m_BoundaryBox.Centre() );
 
     return bestzoom ;
diff --git a/pcbnew/pcbframe.cpp b/pcbnew/pcbframe.cpp
index dfaa98bb75..8490e6c779 100644
--- a/pcbnew/pcbframe.cpp
+++ b/pcbnew/pcbframe.cpp
@@ -314,6 +314,7 @@ PCB_EDIT_FRAME::PCB_EDIT_FRAME( wxWindow* parent, const wxString& title,
 
     m_InternalUnits = PCB_INTERNAL_UNIT;    // Unites internes = 1/10000 inch
     SetScreen( new PCB_SCREEN() );
+    GetScreen()->m_Center = false;          // PCB drawings start in the upper left corner.
 
     // LoadSettings() *after* creating m_LayersManager, because LoadSettings()
     // initialize parameters in m_LayersManager
diff --git a/pcbnew/pcbnew.cpp b/pcbnew/pcbnew.cpp
index 64248aa14b..26430536a5 100644
--- a/pcbnew/pcbnew.cpp
+++ b/pcbnew/pcbnew.cpp
@@ -156,7 +156,6 @@ Changing extension to .brd." ), GetChars( fn.GetFullPath() ) );
     }
 
     frame->Zoom_Automatique( true );
-    frame->GetScreen()->m_FirstRedraw = false;
 
     /* Load file specified in the command line. */
     if( fn.IsOk() )