diff --git a/eeschema/edit_label.cpp b/eeschema/edit_label.cpp
index 8d6eace662..02826443c4 100644
--- a/eeschema/edit_label.cpp
+++ b/eeschema/edit_label.cpp
@@ -73,7 +73,9 @@ static void abortMoveText( EDA_DRAW_PANEL* aPanel, wxDC* aDC )
         wxCHECK_RET( item != NULL, wxT( "Cannot restore undefined last text item." ) );
 
         screen->AddToDrawList( item );
+        // the owner of item is no more parent, this is the draw list of screen:
         parent->SetUndoItem( NULL );
+
         item->Draw( aPanel, aDC, wxPoint( 0, 0 ), GR_DEFAULT_DRAWMODE );
         item->ClearFlags();
     }
diff --git a/eeschema/sch_text.cpp b/eeschema/sch_text.cpp
index 95a261a9e5..03b91e248b 100644
--- a/eeschema/sch_text.cpp
+++ b/eeschema/sch_text.cpp
@@ -337,7 +337,9 @@ void SCH_TEXT::Place( SCH_EDIT_FRAME* frame, wxDC* DC )
 
         undoItem->ClearFlags();
         picker.SetLink( undoItem );
+        // the owner of undoItem is no more frame, this is picker:
         frame->SetUndoItem( NULL );
+
         pickList.PushItem( picker );
         frame->SaveCopyInUndoList( pickList, UR_EXCHANGE_T );
     }
diff --git a/eeschema/schframe.cpp b/eeschema/schframe.cpp
index ee8e5af145..1b50d32045 100644
--- a/eeschema/schframe.cpp
+++ b/eeschema/schframe.cpp
@@ -352,15 +352,20 @@ void SCH_EDIT_FRAME::CreateScreens()
 
 void SCH_EDIT_FRAME::SetUndoItem( const SCH_ITEM* aItem )
 {
-    if( m_undoItem != NULL )
+    // if aItem != NULL, delete a previous m_undoItem, if exists
+    // if aItme = NULL, just clear m_undoItem,
+    // because when calling SetUndoItem( NULL ), we only clear m_undoItem,
+    // because the owner of m_undoItem is no more me.
+    if( aItem && m_undoItem )
     {
         delete m_undoItem;
-        m_undoItem = NULL;
     }
 
+    m_undoItem = NULL;
 
     if( aItem )
         m_undoItem = aItem->Clone();
+
 }
 
 
diff --git a/eeschema/sheet.cpp b/eeschema/sheet.cpp
index 8047362b90..c779dbaf3d 100644
--- a/eeschema/sheet.cpp
+++ b/eeschema/sheet.cpp
@@ -261,7 +261,9 @@ static void ExitSheet( EDA_DRAW_PANEL* aPanel, wxDC* aDC )
         wxCHECK_RET( item != NULL, wxT( "Cannot restore undefined last sheet item." ) );
 
         screen->AddToDrawList( item );
+        // the owner of item is no more parent, this is the draw list of screen:
         parent->SetUndoItem( NULL );
+
         item->Draw( aPanel, aDC, wxPoint( 0, 0 ), GR_DEFAULT_DRAWMODE );
         item->ClearFlags();
         SCH_SHEET* sheet = ( SCH_SHEET* ) item;
diff --git a/pcbnew/editrack.cpp b/pcbnew/editrack.cpp
index 1e10128f05..80eba3b451 100644
--- a/pcbnew/editrack.cpp
+++ b/pcbnew/editrack.cpp
@@ -310,9 +310,9 @@ bool PCB_EDIT_FRAME::Add_45_degrees_Segment( wxDC* DC )
         return false;
     }
 
-    int pas_45 = wxRound( GetScreen()->GetGridSize().x / 2 );
-    if( pas_45 < curTrack->m_Width )
-        pas_45 = curTrack->m_Width;
+    int segm_step_45 = wxRound( GetScreen()->GetGridSize().x / 2 );
+    if( segm_step_45 < ( curTrack->m_Width * 2 ) )
+        segm_step_45 = curTrack->m_Width * 2;
 
     // Test if the segments are horizontal or vertical.
     dx0 = prevTrack->m_End.x - prevTrack->m_Start.x;
@@ -322,10 +322,10 @@ bool PCB_EDIT_FRAME::Add_45_degrees_Segment( wxDC* DC )
     dy1 = curTrack->m_End.y - curTrack->m_Start.y;
 
     // Segments must be of sufficient length.
-    if( MAX( abs( dx0 ), abs( dy0 ) ) < ( pas_45 * 2 ) )
+    if( MAX( abs( dx0 ), abs( dy0 ) ) < ( segm_step_45 * 2 ) )
         return false;
 
-    if( MAX( abs( dx1 ), abs( dy1 ) ) < ( pas_45 * 2 ) )
+    if( MAX( abs( dx1 ), abs( dy1 ) ) < ( segm_step_45 * 2 ) )
         return false;
 
     /* Create a new segment and connect it with the previous 2 segments. */
@@ -347,14 +347,14 @@ bool PCB_EDIT_FRAME::Add_45_degrees_Segment( wxDC* DC )
          * horizontal segment.
          */
         if( dy0 > 0 )
-            newTrack->m_Start.y -= pas_45;
+            newTrack->m_Start.y -= segm_step_45;
         else
-            newTrack->m_Start.y += pas_45;
+            newTrack->m_Start.y += segm_step_45;
 
         if( dx1 > 0 )
-            newTrack->m_End.x += pas_45;
+            newTrack->m_End.x += segm_step_45;
         else
-            newTrack->m_End.x -= pas_45;
+            newTrack->m_End.x -= segm_step_45;
 
         if( Drc_On && BAD_DRC == m_drc->Drc( curTrack, GetBoard()->m_Track ) )
         {
@@ -382,14 +382,14 @@ bool PCB_EDIT_FRAME::Add_45_degrees_Segment( wxDC* DC )
          * (horizontal) and segment 2 (vertical)
          */
         if( dx0 > 0 )
-            newTrack->m_Start.x -= pas_45;
+            newTrack->m_Start.x -= segm_step_45;
         else
-            newTrack->m_Start.x += pas_45;
+            newTrack->m_Start.x += segm_step_45;
 
         if( dy1 > 0 )
-            newTrack->m_End.y += pas_45;
+            newTrack->m_End.y += segm_step_45;
         else
-            newTrack->m_End.y -= pas_45;
+            newTrack->m_End.y -= segm_step_45;
 
         if( Drc_On && BAD_DRC==m_drc->Drc( newTrack, GetBoard()->m_Track ) )
         {