diff --git a/doc/salome/gui/SMESH/images/preview_tmp_data.png b/doc/salome/gui/SMESH/images/preview_tmp_data.png
index be1a12515..6f9fb31b3 100644
Binary files a/doc/salome/gui/SMESH/images/preview_tmp_data.png and b/doc/salome/gui/SMESH/images/preview_tmp_data.png differ
diff --git a/doc/salome/gui/SMESH/input/constructing_meshes.doc b/doc/salome/gui/SMESH/input/constructing_meshes.doc
index 1a5112839..9e5e639be 100644
--- a/doc/salome/gui/SMESH/input/constructing_meshes.doc
+++ b/doc/salome/gui/SMESH/input/constructing_meshes.doc
@@ -38,8 +38,9 @@ creation and specify the meshing parameters on sub-meshes only; then
 only the sub-shapes, for which an algorithm and a hypothesis (if any)
 have been defined will be discretized.
 
-\n Construction of a mesh on a geometry includes at least two (mesh
-creation and computing) of the following steps:
+\n Construction of a mesh on a geometry includes at least two 
+(\ref create_mesh_anchor "mesh creation" and
+\ref compute_anchor "computing") of the following steps:
 <ul>
   <li> \ref create_mesh_anchor "Creation of a mesh object", where you
   can specify meshing parameters to apply to all sub-shapes of the
@@ -262,7 +263,9 @@ information box:
 <h2>Previewing the mesh</h2>
 
 Before \ref compute_anchor "the mesh computation", it is also possible
-to see the mesh preview.
+to see the mesh preview. This operation allows to incrementally
+compute the mesh, dimension by dimension, and to discard an
+unsatisfactory mesh.
 
 For this, select the mesh in the Object Browser. From the \b Mesh menu
 select \b Preview or click "Preview" button in the toolbar or activate
@@ -380,8 +383,8 @@ will see the following information.
 It is equally possible to skip  \ref evaluate_anchor "the Evaluation"
 and \ref preview_anchor "the Preview" and to \b Compute the mesh after
 the hypotheses are assigned. For this, select your mesh in
-the <b>Object Browser</b>. From the \b Mesh menu select \b Compute or
-click "Compute" button of the toolbar.
+the <b>Object Browser</b>. From the \b Mesh menu or the context menu
+select \b Compute or click \a "Compute" button of the toolbar.
 
 <center>
 \image html image28.png
@@ -406,8 +409,9 @@ failure is provided in \b Errors table.
 
 \image html meshcomputationfail.png
 
-After you select an error, <b>Show Sub-shape</b> button allows
-visualizing in magenta the geometrical entity that causes the error.
+After you select an error in \b Errors table, <b>Show Sub-shape</b> button allows
+visualizing in magenta the geometrical entity meshing of which failed
+(Name of this entity or its ID and type is shown in \a Sub-shape column).
 
 <center>
 \image html failed_computation.png 
diff --git a/src/SMESHGUI/SMESHGUI_ComputeDlg.cxx b/src/SMESHGUI/SMESHGUI_ComputeDlg.cxx
index cdcc5d6e7..429531fd2 100644
--- a/src/SMESHGUI/SMESHGUI_ComputeDlg.cxx
+++ b/src/SMESHGUI/SMESHGUI_ComputeDlg.cxx
@@ -1546,11 +1546,11 @@ LightApp_Dialog* SMESHGUI_ComputeOp::dlg() const
 //================================================================================
 
 SMESHGUI_PrecomputeOp::SMESHGUI_PrecomputeOp()
- : SMESHGUI_BaseComputeOp(),
- myDlg( 0 ),
- myOrderMgr( 0 ),
- myActiveDlg( 0 ),
- myPreviewDisplayer( 0 )
+  : SMESHGUI_BaseComputeOp(),
+    myDlg( 0 ),
+    myOrderMgr( 0 ),
+    myActiveDlg( 0 ),
+    myPreviewDisplayer( 0 )
 {
 }
 
@@ -1861,7 +1861,7 @@ void SMESHGUI_PrecomputeOp::onCancel()
       // remove all submeshes for collected shapes
       QMap<int,int>::const_iterator it = myMapShapeId.constBegin();
       for ( ; it != myMapShapeId.constEnd(); ++it )
-        myMesh->ClearSubMesh( *it );
+        myMesh->ClearSubMesh( it.key() );
       isRestoreOrder = true;
     }
   }
@@ -2015,6 +2015,7 @@ SMESHGUI_PrecomputeDlg::SMESHGUI_PrecomputeDlg( QWidget* parent )
 
   setButtonText( OK, tr( "COMPUTE" ) );
   QFrame* main = mainFrame();
+  main->setMinimumWidth( 300 );
 
   QVBoxLayout* layout = new QVBoxLayout( main );