diff --git a/include/wx/aui/framemanager.h b/include/wx/aui/framemanager.h
index 1e6ff1c577..3f59b24a30 100644
--- a/include/wx/aui/framemanager.h
+++ b/include/wx/aui/framemanager.h
@@ -128,13 +128,11 @@ class wxAuiDockInfo;
 class wxAuiDockArt;
 class wxAuiManagerEvent;
 
-#ifndef SWIG
-WX_DECLARE_USER_EXPORTED_OBJARRAY(wxAuiDockInfo, wxAuiDockInfoArray, WXDLLIMPEXP_AUI);
-WX_DECLARE_USER_EXPORTED_OBJARRAY(wxAuiDockUIPart, wxAuiDockUIPartArray, WXDLLIMPEXP_AUI);
-WX_DECLARE_USER_EXPORTED_OBJARRAY(wxAuiPaneInfo, wxAuiPaneInfoArray, WXDLLIMPEXP_AUI);
-WX_DEFINE_USER_EXPORTED_ARRAY_PTR(wxAuiPaneInfo*, wxAuiPaneInfoPtrArray, class WXDLLIMPEXP_AUI);
-WX_DEFINE_USER_EXPORTED_ARRAY_PTR(wxAuiDockInfo*, wxAuiDockInfoPtrArray, class WXDLLIMPEXP_AUI);
-#endif // SWIG
+using wxAuiDockUIPartArray = wxBaseArray<wxAuiDockUIPart>;
+using wxAuiDockInfoArray = wxBaseArray<wxAuiDockInfo>;
+using wxAuiPaneInfoArray = wxBaseArray<wxAuiPaneInfo>;
+using wxAuiDockInfoPtrArray = wxBaseArray<wxAuiDockInfo*>;
+using wxAuiPaneInfoPtrArray = wxBaseArray<wxAuiPaneInfo*>;
 
 extern WXDLLIMPEXP_AUI wxAuiDockInfo wxAuiNullDockInfo;
 extern WXDLLIMPEXP_AUI wxAuiPaneInfo wxAuiNullPaneInfo;
@@ -615,6 +613,11 @@ protected:
 
     void* m_reserved;
 
+private:
+    // Return the index in m_uiParts corresponding to the current value of
+    // m_actionPart. If m_actionPart is null, returns wxNOT_FOUND.
+    int GetActionPartIndex() const;
+
 #ifndef SWIG
     wxDECLARE_EVENT_TABLE();
     wxDECLARE_CLASS(wxAuiManager);
diff --git a/src/aui/framemanager.cpp b/src/aui/framemanager.cpp
index c2fbe3ffbc..d90a07a763 100644
--- a/src/aui/framemanager.cpp
+++ b/src/aui/framemanager.cpp
@@ -42,11 +42,6 @@
 
 WX_CHECK_BUILD_OPTIONS("wxAUI")
 
-#include "wx/arrimpl.cpp"
-WX_DEFINE_OBJARRAY(wxAuiDockUIPartArray)
-WX_DEFINE_OBJARRAY(wxAuiDockInfoArray)
-WX_DEFINE_OBJARRAY(wxAuiPaneInfoArray)
-
 wxAuiPaneInfo wxAuiNullPaneInfo;
 wxAuiDockInfo wxAuiNullDockInfo;
 wxDEFINE_EVENT( wxEVT_AUI_PANE_BUTTON, wxAuiManagerEvent );
@@ -628,6 +623,20 @@ wxAuiManager::~wxAuiManager()
     delete m_art;
 }
 
+int wxAuiManager::GetActionPartIndex() const
+{
+    int n = 0;
+    for ( const auto& uiPart : m_uiParts )
+    {
+        if ( &uiPart == m_actionPart )
+            return n;
+
+        ++n;
+    }
+
+    return wxNOT_FOUND;
+}
+
 void wxAuiManager::OnSysColourChanged(wxSysColourChangedEvent& event)
 {
     m_art->UpdateColoursFromSystem();
@@ -1239,12 +1248,27 @@ bool wxAuiManager::DetachPane(wxWindow* window)
             // just in case the caller doesn't call Update() immediately after
             // the DetachPane() call.  This prevets obscure crashes which would
             // happen at window repaint if the caller forgets to call Update()
+            int actionPartIndex = GetActionPartIndex();
             int pi, part_count;
             for (pi = 0, part_count = (int)m_uiParts.GetCount(); pi < part_count; ++pi)
             {
                 wxAuiDockUIPart& part = m_uiParts.Item(pi);
                 if (part.pane == &p)
                 {
+                    if (actionPartIndex != wxNOT_FOUND)
+                    {
+                        if (pi == actionPartIndex)
+                        {
+                            // We're removing the action part, so invalidate it.
+                            actionPartIndex = wxNOT_FOUND;
+                        }
+                        else if (pi < actionPartIndex)
+                        {
+                            // Just adjust the action part index.
+                            actionPartIndex--;
+                        }
+                    }
+
                     m_uiParts.RemoveAt(pi);
                     part_count--;
                     pi--;
@@ -1252,6 +1276,11 @@ bool wxAuiManager::DetachPane(wxWindow* window)
                 }
             }
 
+            // Update m_actionPart pointer too to ensure that it remains valid.
+            m_actionPart = actionPartIndex == wxNOT_FOUND
+                            ? nullptr
+                            : &m_uiParts.Item(actionPartIndex);
+
             m_panes.RemoveAt(i);
             return true;
         }
@@ -4542,7 +4571,7 @@ void wxAuiManager::OnMotion(wxMouseEvent& event)
         if (m_currentDragItem != -1)
             m_actionPart = & (m_uiParts.Item(m_currentDragItem));
         else
-            m_currentDragItem = m_uiParts.Index(* m_actionPart);
+            m_currentDragItem = GetActionPartIndex();
 
         if (m_actionPart)
         {