Order array has to have the same size as item list in wxRearrangeList

Number of indices stored in the internal order array has to be the same as
number of the items, so whenever item is added or removed, order array
has to be adjusted accordingly.

Closes wxWidgets#17836.

include/wx/rearrangectrl.h

@@ -99,6 +99,10 @@ class WXDLLIMPEXP_CORE wxRearrangeList : public wxCheckListBox
     // Override this to keep our m_order array in sync with the real item state.
     virtual void Check(unsigned int item, bool check = true) wxOVERRIDE;
 
+    int DoInsertOneItem(const wxString& item, unsigned int pos) wxOVERRIDE;
+    void DoDeleteOneItem(unsigned int n) wxOVERRIDE;
+    void DoClear() wxOVERRIDE;
+
 private:
     // swap two items at the given positions in the listbox
     void Swap(int pos1, int pos2);

src/common/rearrangectrl.cpp

@@ -70,6 +70,7 @@ bool wxRearrangeList::Create(wxWindow *parent,
     }
 
     // do create the real control
+    m_order.reserve(count);
     if ( !wxCheckListBox::Create(parent, id, pos, size, itemsInOrder,
                                  style, validator, name) )
         return false;
@@ -83,10 +84,9 @@ bool wxRearrangeList::Create(wxWindow *parent,
             // which would also update m_order itself.
             wxCheckListBox::Check(n);
         }
+        m_order[n] = order[n];
     }
 
-    m_order = order;
-
     return true;
 }
 
@@ -188,6 +188,46 @@ void wxRearrangeList::OnCheck(wxCommandEvent& event)
         m_order[n] = ~m_order[n];
 }
 
+int wxRearrangeList::DoInsertOneItem(const wxString& item, unsigned int pos)
+{
+    wxCheckListBox::DoInsertOneItem(item, pos);
+    // Item is not checked initially.
+    const int idx = ~m_order.size();
+    m_order.Insert(idx, pos);
+    return pos;
+}
+
+void wxRearrangeList::DoDeleteOneItem(unsigned int n)
+{
+    wxCheckListBox::DoDeleteOneItem(n);
+    int idxDeleted = m_order[n];
+    if ( idxDeleted < 0 )
+        idxDeleted = ~idxDeleted;
+    m_order.RemoveAt(n);
+    // Remaining items have to be reindexed.
+    for( size_t i = 0; i < m_order.size(); i++ )
+    {
+        int idx = m_order[i];
+        if ( idx < 0 )
+        {
+            idx = ~idx;
+            if ( idx > idxDeleted )
+                m_order[i] = ~(idx-1);
+        }
+        else
+        {
+            if ( idx > idxDeleted )
+                m_order[i] = idx-1;
+        }
+    }
+}
+
+void wxRearrangeList::DoClear()
+{
+    wxCheckListBox::DoClear();
+    m_order.Clear();
+}
+
 // ============================================================================
 // wxRearrangeCtrl implementation
 // ============================================================================