HIERARCHY_NAVIG_DLG: fix crash when in a subsheet one open the dialog

and switch to the paren sheet from the context menu.

Mainly, change the way the dialog is managed from the sch_edit_frame:
the pointer to find the created dialog is replaced by a call to wxWidows::FindWindowByName().

Using a pointer set and cleared by events is a recipe for crashes.

eeschema/hierarch.cpp

@@ -80,7 +80,7 @@ HIERARCHY_TREE::HIERARCHY_TREE( HIERARCHY_NAVIG_DLG* parent ) :
 
 HIERARCHY_NAVIG_DLG::HIERARCHY_NAVIG_DLG( SCH_EDIT_FRAME* aParent ) :
     DIALOG_SHIM( aParent, wxID_ANY, _( "Navigator" ), wxDefaultPosition, wxDefaultSize,
-                 wxDEFAULT_DIALOG_STYLE | wxRESIZE_BORDER )
+                 wxDEFAULT_DIALOG_STYLE | wxRESIZE_BORDER, HIERARCHY_NAVIG_DLG_WNAME )
 {
     wxASSERT( dynamic_cast< SCH_EDIT_FRAME* >( aParent ) );
 
@@ -130,6 +130,9 @@ HIERARCHY_NAVIG_DLG::HIERARCHY_NAVIG_DLG( SCH_EDIT_FRAME* aParent ) :
     Bind( wxEVT_TREE_ITEM_ACTIVATED, &HIERARCHY_NAVIG_DLG::onSelectSheetPath, this );
     // Manage a simple click on a selection, if the selection changes
     Bind( wxEVT_TREE_SEL_CHANGED, &HIERARCHY_NAVIG_DLG::onSelectSheetPath, this );
+
+	// Connect close event for the dialog:
+	this->Connect( wxEVT_CLOSE_WINDOW, wxCloseEventHandler( HIERARCHY_NAVIG_DLG::OnCloseNav ) );
 }
 
 
@@ -138,6 +141,7 @@ HIERARCHY_NAVIG_DLG::~HIERARCHY_NAVIG_DLG()
     Unbind( wxEVT_TREE_ITEM_ACTIVATED, &HIERARCHY_NAVIG_DLG::onSelectSheetPath, this );
     Unbind( wxEVT_TREE_SEL_CHANGED, &HIERARCHY_NAVIG_DLG::onSelectSheetPath, this );
     m_Tree->Disconnect( wxEVT_CHAR, wxKeyEventHandler( HIERARCHY_TREE::onChar ) );
+	this->Disconnect( wxEVT_CLOSE_WINDOW, wxCloseEventHandler( HIERARCHY_NAVIG_DLG::OnCloseNav ) );
 }
 
 
@@ -184,12 +188,16 @@ void HIERARCHY_NAVIG_DLG::buildHierarchyTree( SCH_SHEET_PATH* aList, wxTreeItemI
 
 void HIERARCHY_NAVIG_DLG::UpdateHierarchyTree()
 {
+    Freeze();
+
     m_currSheet       = m_SchFrameEditor->GetCurrentSheet();
     wxTreeItemId root = m_Tree->GetRootItem();
     m_Tree->DeleteChildren( root );
     m_list.clear();
     m_list.push_back( g_RootSheet );
     buildHierarchyTree( &m_list, &root );
+
+    Thaw();
 }
 
 void HIERARCHY_NAVIG_DLG::onSelectSheetPath( wxTreeEvent& event )
@@ -200,15 +208,18 @@ void HIERARCHY_NAVIG_DLG::onSelectSheetPath( wxTreeEvent& event )
     wxTreeItemId ItemSel = m_Tree->GetSelection();
     m_SchFrameEditor->SetCurrentSheet(( (TreeItemData*) m_Tree->GetItemData( ItemSel ) )->m_SheetPath );
     m_SchFrameEditor->DisplayCurrentSheet();
+
     if( m_SchFrameEditor->GetNavigatorStaysOpen() == false )
         Close( true );
 }
 
-void HIERARCHY_NAVIG_DLG::OnClose( wxCloseEvent& event )
+
+void HIERARCHY_NAVIG_DLG::OnCloseNav( wxCloseEvent& event )
 {
-    m_SchFrameEditor->CloseHierarchyNavigator();
+    Destroy();
 }
 
+
 void SCH_EDIT_FRAME::DisplayCurrentSheet()
 {
     m_toolManager->RunAction( ACTIONS::cancelInteractive, true );

eeschema/hierarch.h

@@ -31,6 +31,9 @@
 #include <wx/imaglist.h>
 #include <wx/treectrl.h>
 
+// The window name of the hierarchy navigator, used to find it
+#define HIERARCHY_NAVIG_DLG_WNAME "hierarchy_navig_dlg"
+
 class SCH_EDIT_FRAME;
 class SCH_SHEET_PATH;
 
@@ -65,7 +68,9 @@ public:
     HIERARCHY_NAVIG_DLG( SCH_EDIT_FRAME* aParent );
 
     ~HIERARCHY_NAVIG_DLG();
-    void OnClose( wxCloseEvent& event );
+
+    void OnCloseNav( wxCloseEvent& event );
+
     /**
      * Update the hierarchical tree of the schematic.
      */

eeschema/sch_edit_frame.cpp

@@ -248,7 +248,6 @@ SCH_EDIT_FRAME::SCH_EDIT_FRAME( KIWAY* aKiway, wxWindow* aParent ):
 
     m_findReplaceDialog = nullptr;
     m_findReplaceStatusPopup = nullptr;
-    m_hierarchyDialog        = nullptr;
 
     SetForceHVLines( true );
     SetSpiceAdjustPassiveValues( false );
@@ -562,10 +561,9 @@ void SCH_EDIT_FRAME::OnCloseWindow( wxCloseEvent& aEvent )
         m_findReplaceDialog = nullptr;
     }
 
-    if( m_hierarchyDialog )
+    if( FindHierarchyNavigator() )
     {
-        m_hierarchyDialog->Destroy();
-        m_hierarchyDialog = nullptr;
+        FindHierarchyNavigator()->Close( true );
     }
 
     SCH_SCREENS screens;
@@ -676,26 +674,33 @@ wxFindReplaceData* SCH_EDIT_FRAME::GetFindReplaceData()
     return nullptr;
 }
 
+
+HIERARCHY_NAVIG_DLG* SCH_EDIT_FRAME::FindHierarchyNavigator()
+{
+    wxWindow* navigator = wxWindow::FindWindowByName( HIERARCHY_NAVIG_DLG_WNAME );
+
+    return static_cast< HIERARCHY_NAVIG_DLG* >( navigator );
+}
+
 void SCH_EDIT_FRAME::UpdateHierarchyNavigator( bool aForceUpdate )
 {
-
     if( aForceUpdate )
     {
-        if( m_hierarchyDialog )
-            CloseHierarchyNavigator();
+        if( FindHierarchyNavigator() )
+            FindHierarchyNavigator()->Close();
 
-        m_hierarchyDialog = new HIERARCHY_NAVIG_DLG( this );
-        m_hierarchyDialog->Connect(
-                wxEVT_CLOSE_WINDOW, wxCloseEventHandler( HIERARCHY_NAVIG_DLG::OnClose ) );
-        m_hierarchyDialog->Show( true );
+        HIERARCHY_NAVIG_DLG* hierarchyDialog = new HIERARCHY_NAVIG_DLG( this );
+
+        hierarchyDialog->Show( true );
     }
     else
     {
-        if( m_hierarchyDialog )
-            m_hierarchyDialog->UpdateHierarchyTree();
+        if( FindHierarchyNavigator() )
+            FindHierarchyNavigator()->UpdateHierarchyTree();
     }
 }
 
+
 void SCH_EDIT_FRAME::ShowFindReplaceDialog( bool aReplace )
 {
     if( m_findReplaceStatusPopup )
@@ -748,11 +753,6 @@ void SCH_EDIT_FRAME::OnFindDialogClose()
     m_findReplaceDialog = nullptr;
 }
 
-void SCH_EDIT_FRAME::CloseHierarchyNavigator()
-{
-    m_hierarchyDialog->Destroy();
-    m_hierarchyDialog = nullptr;
-}
 
 void SCH_EDIT_FRAME::OnLoadFile( wxCommandEvent& event )
 {

eeschema/sch_edit_frame.h

@@ -139,7 +139,6 @@ private:
 
     DIALOG_SCH_FIND*        m_findReplaceDialog;
     STATUS_TEXT_POPUP*      m_findReplaceStatusPopup;
-    HIERARCHY_NAVIG_DLG*    m_hierarchyDialog;
 
     /// Flag to indicate show hidden pins.
     bool        m_showAllPins;
@@ -357,11 +356,16 @@ public:
 
     /**
      * Run the Hierarchy Navigator dialog.
-     * @param aForceUpdate When true, creates a new dialog. And if a dialog
+     * @param aForceUpdate: When true, creates a new dialog. And if a dialog
      * already exist, it destroys it first.
      */
     void UpdateHierarchyNavigator( bool aForceUpdate = false );
 
+    /**
+      * @return a reference to the Hierarchy Navigator dialog if exists, or nullptr.
+     */
+    HIERARCHY_NAVIG_DLG* FindHierarchyNavigator();
+
     void ShowFindReplaceStatus( const wxString& aMsg );
     void ClearFindReplaceStatus();
 
@@ -375,11 +379,6 @@ public:
      */
     void OnFindDialogClose();
 
-    /**
-     * Destroy the Hierarchy Navigator dialog.
-     */
-    void CloseHierarchyNavigator();
-
     /**
      * Breaks a single segment into two at the specified point.
      *