diff --git a/include/wx/propgrid/propgrid.h b/include/wx/propgrid/propgrid.h
index e41451d8c8..ccb43d2f2a 100644
--- a/include/wx/propgrid/propgrid.h
+++ b/include/wx/propgrid/propgrid.h
@@ -1062,7 +1062,12 @@ public:
     wxPropertyGridHitTestResult HitTest( const wxPoint& pt ) const;
 
     /** Returns true if any property has been modified by the user. */
-    bool IsAnyModified() const { return (m_pState->m_anyModified>0); }
+    bool IsAnyModified() const
+#ifdef WXWIN_COMPATIBILITY_3_0
+         { return m_pState->m_anyModified != (unsigned char)false; }
+#else
+         { return m_pState->m_anyModified; }
+#endif
 
     /**
         It is recommended that you call this function any time your code causes
diff --git a/include/wx/propgrid/propgridpagestate.h b/include/wx/propgrid/propgridpagestate.h
index b6bec54b73..8eb910bceb 100644
--- a/include/wx/propgrid/propgridpagestate.h
+++ b/include/wx/propgrid/propgridpagestate.h
@@ -470,7 +470,7 @@ public:
         if ( m_vhCalcPending )
         {
             RecalculateVirtualHeight();
-            m_vhCalcPending = 0;
+            m_vhCalcPending = false;
         }
     }
 
@@ -653,7 +653,7 @@ public:
     */
     void VirtualHeightChanged()
     {
-        m_vhCalcPending = 1;
+        m_vhCalcPending = true;
     }
 
     /** Base append. */
@@ -737,6 +737,7 @@ protected:
     /** Indicates total virtual height of visible properties. */
     unsigned int                m_virtualHeight;
 
+#ifdef WXWIN_COMPATIBILITY_3_0
     /** 1 if m_lastCaption is also the bottommost caption. */
     unsigned char               m_lastCaptionBottomnest;
 
@@ -750,6 +751,21 @@ protected:
     unsigned char               m_anyModified;
 
     unsigned char               m_vhCalcPending;
+#else
+    /** True if m_lastCaption is also the bottommost caption. */
+    bool                        m_lastCaptionBottomnest;
+
+    /** True: items appended/inserted, so stuff needs to be done before drawing;
+        If m_virtualHeight == 0, then calcylatey's must be done.
+        Otherwise just sort.
+    */
+    bool                        m_itemsAdded;
+
+    /** True if any value is modified. */
+    bool                        m_anyModified;
+
+    bool                        m_vhCalcPending;
+#endif // WXWIN_COMPATIBILITY_3_0
 
     /** True if splitter has been pre-set by the application. */
     bool                        m_isSplitterPreSet;
diff --git a/src/propgrid/propgrid.cpp b/src/propgrid/propgrid.cpp
index 0aada2d7d5..1e6d19f202 100644
--- a/src/propgrid/propgrid.cpp
+++ b/src/propgrid/propgrid.cpp
@@ -608,7 +608,7 @@ void wxPropertyGrid::SetWindowStyleFlag( long style )
             if ( !IsFrozen() )
                 PrepareAfterItemsAdded();
             else
-                m_pState->m_itemsAdded = 1;
+                m_pState->m_itemsAdded = true;
         }
     #if wxPG_SUPPORT_TOOLTIPS
         if ( !(old_style & wxPG_TOOLTIPS) && (style & wxPG_TOOLTIPS) )
@@ -1547,7 +1547,7 @@ void wxPropertyGrid::PrepareAfterItemsAdded()
 {
     if ( !m_pState || !m_pState->m_itemsAdded ) return;
 
-    m_pState->m_itemsAdded = 0;
+    m_pState->m_itemsAdded = false;
 
     if ( m_windowStyle & wxPG_AUTO_SORT )
         Sort(wxPG_SORT_TOP_LEVEL_ONLY);
@@ -2683,12 +2683,12 @@ bool wxPropertyGrid::EnableCategories( bool enable )
     {
         if ( m_windowStyle & wxPG_AUTO_SORT )
         {
-            m_pState->m_itemsAdded = 1; // force
+            m_pState->m_itemsAdded = true; // force
             PrepareAfterItemsAdded();
         }
     }
     else
-        m_pState->m_itemsAdded = 1;
+        m_pState->m_itemsAdded = true;
 
     // No need for RecalculateVirtualSize() here - it is already called in
     // wxPropertyGridPageState method above.
@@ -2764,7 +2764,7 @@ void wxPropertyGrid::SwitchState( wxPropertyGridPageState* pNewState )
         Refresh();
     }
     else
-        m_pState->m_itemsAdded = 1;
+        m_pState->m_itemsAdded = true;
 }
 
 // -----------------------------------------------------------------------
@@ -3325,7 +3325,7 @@ bool wxPropertyGrid::DoPropertyChanged( wxPGProperty* p, unsigned int selFlags )
 
     wxPGProperty* selected = GetSelection();
 
-    m_pState->m_anyModified = 1;
+    m_pState->m_anyModified = true;
 
     // Maybe need to update control
     wxASSERT( m_chgInfo_changedProperty != NULL );
diff --git a/src/propgrid/propgridpagestate.cpp b/src/propgrid/propgridpagestate.cpp
index cf032ab748..9912fa5b29 100644
--- a/src/propgrid/propgridpagestate.cpp
+++ b/src/propgrid/propgridpagestate.cpp
@@ -209,10 +209,10 @@ wxPropertyGridPageState::wxPropertyGridPageState()
     m_currentCategory = NULL;
     m_width = 0;
     m_virtualHeight = 0;
-    m_lastCaptionBottomnest = 1;
-    m_itemsAdded = 0;
-    m_anyModified = 0;
-    m_vhCalcPending = 0;
+    m_lastCaptionBottomnest = true;
+    m_itemsAdded = false;
+    m_anyModified = false;
+    m_vhCalcPending = false;
     m_colWidths.push_back( wxPG_DEFAULT_SPLITTERX );
     m_colWidths.push_back( wxPG_DEFAULT_SPLITTERX );
     m_fSplitterX = wxPG_DEFAULT_SPLITTERX;
@@ -311,11 +311,11 @@ void wxPropertyGridPageState::DoClear()
         m_dictName.clear();
 
         m_currentCategory = NULL;
-        m_lastCaptionBottomnest = 1;
-        m_itemsAdded = 0;
+        m_lastCaptionBottomnest = true;
+        m_itemsAdded = false;
 
         m_virtualHeight = 0;
-        m_vhCalcPending = 0;
+        m_vhCalcPending = false;
     }
 }
 
@@ -746,7 +746,7 @@ bool wxPropertyGridPageState::PrepareAfterItemsAdded()
 
     wxPropertyGrid* pg = GetGrid();
 
-    m_itemsAdded = 0;
+    m_itemsAdded = false;
 
     if ( pg->HasFlag(wxPG_AUTO_SORT) )
         DoSort(wxPG_SORT_TOP_LEVEL_ONLY);
@@ -1823,7 +1823,7 @@ wxPGProperty* wxPropertyGridPageState::DoInsert( wxPGProperty* parent, int index
         // This is a category caption item.
 
         // Last caption is not the bottom one (this info required by append)
-        m_lastCaptionBottomnest = 0;
+        m_lastCaptionBottomnest = false;
     }
 
     // Only add name to hashmap if parent is root or category
@@ -1835,7 +1835,7 @@ wxPGProperty* wxPropertyGridPageState::DoInsert( wxPGProperty* parent, int index
 
     property->UpdateParentValues();
 
-    m_itemsAdded = 1;
+    m_itemsAdded = true;
 
     return property;
 }
@@ -2024,7 +2024,7 @@ void wxPropertyGridPageState::DoDelete( wxPGProperty* item, bool doDelete )
         item->OnDetached(this, pg);
     }
 
-    m_itemsAdded = 1; // Not a logical assignment (but required nonetheless).
+    m_itemsAdded = true; // Not a logical assignment (but required nonetheless).
 
     VirtualHeightChanged();
 }