diff --git a/src/aui/framemanager.cpp b/src/aui/framemanager.cpp
index ca6ea2b3c9..b4c4aca0ce 100644
--- a/src/aui/framemanager.cpp
+++ b/src/aui/framemanager.cpp
@@ -1842,8 +1842,8 @@ void wxAuiManager::LayoutAddPane(wxSizer* cont,
     // value that the pane will receive
     int pane_proportion = pane.dock_proportion;
 
-    wxBoxSizer* horz_pane_sizer = new wxBoxSizer(wxHORIZONTAL);
-    wxBoxSizer* vert_pane_sizer = new wxBoxSizer(wxVERTICAL);
+    wxAuiProportionalBoxSizer* horz_pane_sizer = new wxAuiProportionalBoxSizer(wxHORIZONTAL);
+    wxAuiProportionalBoxSizer* vert_pane_sizer = new wxAuiProportionalBoxSizer(wxVERTICAL);
 
     if (pane.HasGripper())
     {
@@ -1865,7 +1865,7 @@ void wxAuiManager::LayoutAddPane(wxSizer* cont,
     if (pane.HasCaption())
     {
         // create the caption sizer
-        wxBoxSizer* caption_sizer = new wxBoxSizer(wxHORIZONTAL);
+        wxAuiProportionalBoxSizer* caption_sizer = new wxAuiProportionalBoxSizer(wxHORIZONTAL);
 
         sizer_item = caption_sizer->Add(1, caption_size, 1, wxEXPAND);
 
@@ -2147,7 +2147,7 @@ wxSizer* wxAuiManager::LayoutAll(wxAuiPaneInfoArray& panes,
                                  wxAuiDockUIPartArray& uiparts,
                                  bool spacer_only)
 {
-    wxBoxSizer* container = new wxBoxSizer(wxVERTICAL);
+    wxAuiProportionalBoxSizer* container = new wxAuiProportionalBoxSizer(wxVERTICAL);
 
     int pane_border_size = m_art->GetMetric(wxAUI_DOCKART_PANE_BORDER_SIZE);
     int caption_size = m_art->GetMetric(wxAUI_DOCKART_CAPTION_SIZE);
@@ -2430,7 +2430,7 @@ wxSizer* wxAuiManager::LayoutAll(wxAuiPaneInfoArray& panes,
 
         // create a container which will hold this layer's
         // docks (top, bottom, left, right)
-        cont = new wxBoxSizer(wxVERTICAL);
+        cont = new wxAuiProportionalBoxSizer(wxVERTICAL);
 
 
         // find any top docks in this layer
@@ -2445,7 +2445,7 @@ wxSizer* wxAuiManager::LayoutAll(wxAuiPaneInfoArray& panes,
         // fill out the middle layer (which consists
         // of left docks, content area and right docks)
 
-        middle = new wxBoxSizer(wxHORIZONTAL);
+        middle = new wxAuiProportionalBoxSizer(wxHORIZONTAL);
 
         // find any left docks in this layer
         FindDocks(docks, wxAUI_DOCK_LEFT, layer, -1, arr);
@@ -2514,7 +2514,7 @@ wxSizer* wxAuiManager::LayoutAll(wxAuiPaneInfoArray& panes,
     {
         // no sizer available, because there are no docks,
         // therefore we will create a simple background area
-        cont = new wxBoxSizer(wxVERTICAL);
+        cont = new wxAuiProportionalBoxSizer(wxVERTICAL);
         wxSizerItem* sizer_item = cont->Add(1,1, 1, wxEXPAND);
         wxAuiDockUIPart part;
         part.type = wxAuiDockUIPart::typeBackground;
@@ -4176,26 +4176,84 @@ bool wxAuiManager::DoEndResizeAction(wxMouseEvent& event)
     // resize the dock or the pane
     if (m_action_part && m_action_part->type==wxAuiDockUIPart::typeDockSizer)
     {
+        // first, we must calculate the maximum size the dock may be
+        int sash_size = m_art->GetMetric(wxAUI_DOCKART_SASH_SIZE);
+
+        int used_width = 0, used_height = 0;
+
+        wxSize client_size = m_frame->GetClientSize();
+        
+        size_t dock_i, dock_count = m_docks.GetCount();
+        for (dock_i = 0; dock_i < dock_count; ++dock_i)
+        {
+            wxAuiDockInfo& dock = m_docks.Item(dock_i);
+            if (dock.dock_direction == wxAUI_DOCK_TOP ||
+                dock.dock_direction == wxAUI_DOCK_BOTTOM)
+            {
+                used_height += dock.size;
+            }
+            if (dock.dock_direction == wxAUI_DOCK_LEFT ||
+                dock.dock_direction == wxAUI_DOCK_RIGHT)
+            {
+                used_width += dock.size;
+            }
+            if (dock.resizable)
+                used_width += sash_size;
+        }
+        
+        
+        int available_width = client_size.GetWidth() - used_width;
+        int available_height = client_size.GetHeight() - used_height;
+        
+        
+#if wxUSE_STATUSBAR
+        // if there's a status control, the available
+        // height decreases accordingly
+        if (m_frame && m_frame->IsKindOf(CLASSINFO(wxFrame)))
+        {
+            wxFrame* frame = static_cast<wxFrame*>(m_frame);
+            wxStatusBar* status = frame->GetStatusBar();
+            if (status)
+            {
+                wxSize status_client_size = status->GetClientSize();
+                available_height -= status_client_size.GetHeight();
+            }
+        }
+#endif
+    
         wxRect& rect = m_action_part->dock->rect;
 
         wxPoint new_pos(event.m_x - m_action_offset.x,
             event.m_y - m_action_offset.y);
-
+        int new_size, old_size = m_action_part->dock->size;
+        
         switch (m_action_part->dock->dock_direction)
         {
         case wxAUI_DOCK_LEFT:
-            m_action_part->dock->size = new_pos.x - rect.x;
+            new_size = new_pos.x - rect.x;
+            if (new_size-old_size > available_width)
+                new_size = old_size+available_width;
+            m_action_part->dock->size = new_size;
             break;
         case wxAUI_DOCK_TOP:
-            m_action_part->dock->size = new_pos.y - rect.y;
+            new_size = new_pos.y - rect.y;
+            if (new_size-old_size > available_height)
+                new_size = old_size+available_height;
+            m_action_part->dock->size = new_size;
             break;
         case wxAUI_DOCK_RIGHT:
-            m_action_part->dock->size = rect.x + rect.width -
-                new_pos.x - m_action_part->rect.GetWidth();
+            new_size = rect.x + rect.width - new_pos.x -
+                       m_action_part->rect.GetWidth();
+            if (new_size-old_size > available_width)
+                new_size = old_size+available_width;
+            m_action_part->dock->size = new_size;
             break;
         case wxAUI_DOCK_BOTTOM:
-            m_action_part->dock->size = rect.y + rect.height -
+            new_size = rect.y + rect.height -
                 new_pos.y - m_action_part->rect.GetHeight();
+            if (new_size-old_size > available_height)
+                new_size = old_size+available_height;
+            m_action_part->dock->size = new_size;
             break;
         }