diff --git a/include/wx/osx/button.h b/include/wx/osx/button.h
index 8959d9b142..75108eeb24 100644
--- a/include/wx/osx/button.h
+++ b/include/wx/osx/button.h
@@ -89,7 +89,7 @@ public:
              const wxString& label = wxEmptyString,
              const wxPoint& pos = wxDefaultPosition,
              const wxSize& size = wxDefaultSize,
-             long style = 0,
+             long style = wxBORDER_NONE,
              const wxValidator& validator = wxDefaultValidator,
              const wxString& name = wxButtonNameStr)
     {
@@ -101,7 +101,7 @@ public:
                 const wxString& label = wxEmptyString,
                 const wxPoint& pos = wxDefaultPosition,
                 const wxSize& size = wxDefaultSize,
-                long style = 0,
+                long style = wxBORDER_NONE,
                 const wxValidator& validator = wxDefaultValidator,
                 const wxString& name = wxButtonNameStr);
 
diff --git a/src/generic/collpaneg.cpp b/src/generic/collpaneg.cpp
index b032263be6..894345be6b 100644
--- a/src/generic/collpaneg.cpp
+++ b/src/generic/collpaneg.cpp
@@ -87,22 +87,22 @@ bool wxGenericCollapsiblePane::Create(wxWindow *parent,
 
     m_strLabel = label;
 
-#if defined( __WXMAC__ ) && !defined(__WXUNIVERSAL__)
-    // on Mac we use the disclosure triangle
-    m_pStaticLine = NULL;
-    m_pButton = new wxDisclosureTriangle(this, wxID_ANY, GetBtnLabel(),
-                                         wxDefaultPosition, wxDefaultSize,
-                                         style & wxBORDER_MASK);
+    // sizer containing the expand button and possibly a static line
     m_sz = new wxBoxSizer(wxHORIZONTAL);
-    m_sz->Add(m_pButton, wxSizerFlags(1).Expand());
+
+#if defined( __WXMAC__ ) && !defined(__WXUNIVERSAL__)
+    // on Mac we use the special disclosure triangle button
+    m_pStaticLine = NULL;
+    m_pButton = new wxDisclosureTriangle(this, wxID_ANY, GetBtnLabel());
+    m_sz->Add(m_pButton);
 #else
     // create children and lay them out using a wxBoxSizer
     // (so that we automatically get RTL features)
     m_pButton = new wxButton(this, wxID_ANY, GetBtnLabel(), wxPoint(0, 0),
                              wxDefaultSize, wxBU_EXACTFIT);
     m_pStaticLine = new wxStaticLine(this, wxID_ANY);
+
     // on other platforms we put the static line and the button horizontally
-    m_sz = new wxBoxSizer(wxHORIZONTAL);
     m_sz->Add(m_pButton, 0, wxLEFT|wxTOP|wxBOTTOM, GetBorder());
     m_sz->Add(m_pStaticLine, 1, wxALIGN_CENTER|wxLEFT|wxRIGHT, GetBorder());
 #endif
diff --git a/src/osx/cocoa/button.mm b/src/osx/cocoa/button.mm
index 9dbcbee2da..355b77707a 100644
--- a/src/osx/cocoa/button.mm
+++ b/src/osx/cocoa/button.mm
@@ -130,6 +130,26 @@ private:
     }
 };
 
+// set bezel style depending on the wxBORDER_XXX flags specified by the style
+void SetBezelStyleFromBorderFlags(NSButton *v, long style)
+{
+    if ( style & wxBORDER_NONE )
+    {
+        [v setBezelStyle:NSShadowlessSquareBezelStyle];
+        [v setBordered:NO];
+    }
+    else // we do have a border
+    {
+        // see trac #11128 for a thorough discussion
+        if ( (style & wxBORDER_MASK) == wxBORDER_RAISED )
+            [v setBezelStyle:NSRegularSquareBezelStyle];
+        else if ( (style & wxBORDER_MASK) == wxBORDER_SUNKEN )
+            [v setBezelStyle:NSSmallSquareBezelStyle];
+        else
+            [v setBezelStyle:NSShadowlessSquareBezelStyle];
+    }
+}
+
 } // anonymous namespace
 
 wxWidgetImplType* wxWidgetImpl::CreateButton( wxWindowMac* wxpeer,
@@ -167,8 +187,8 @@ void wxWidgetCocoaImpl::SetDefaultButton( bool isDefault )
 
 void wxWidgetCocoaImpl::PerformClick()
 {
-    if ([m_osxView isKindOfClass:[NSControl class]]) 
-        [(NSControl*)m_osxView performClick:nil]; 
+    if ([m_osxView isKindOfClass:[NSControl class]])
+        [(NSControl*)m_osxView performClick:nil];
 }
 
 #if wxUSE_BMPBUTTON
@@ -184,33 +204,18 @@ wxWidgetImplType* wxWidgetImpl::CreateBitmapButton( wxWindowMac* wxpeer,
 {
     NSRect r = wxOSXGetFrameForControl( wxpeer, pos , size ) ;
     wxNSButton* v = [[wxNSButton alloc] initWithFrame:r];
-    
-    // trying to get as close as possible to flags
-    if ( style & wxBORDER_NONE )
-    {
-        [v setBezelStyle:NSShadowlessSquareBezelStyle];
-        [v setBordered:NO]; 
-    }
-    else
-    {
-        // see trac #11128 for a thorough discussion
-        if ( (style & wxBORDER_MASK) == wxBORDER_RAISED )
-            [v setBezelStyle:NSRegularSquareBezelStyle];
-        else if ( (style & wxBORDER_MASK) == wxBORDER_SUNKEN )
-            [v setBezelStyle:NSSmallSquareBezelStyle];
-        else
-            [v setBezelStyle:NSShadowlessSquareBezelStyle];
-    }
-    
+
+    SetBezelStyleFromBorderFlags(v, style);
+
     if (bitmap.Ok())
         [v setImage:bitmap.GetNSImage() ];
-    
+
     [v setButtonType:NSMomentaryPushInButton];
     wxWidgetCocoaImpl* c = new wxButtonCocoaImpl( wxpeer, v );
     return c;
 }
 
-#endif
+#endif // wxUSE_BMPBUTTON
 
 //
 // wxDisclosureButton implementation
@@ -262,7 +267,6 @@ static const char * disc_triangle_xpm[] = {
 - (id) initWithFrame:(NSRect) frame
 {
     self = [super initWithFrame:frame];
-    [self setBezelStyle:NSSmallSquareBezelStyle];
     isOpen = NO;
     [self setImagePosition:NSImageLeft];
     [self updateImage];
@@ -348,16 +352,19 @@ public :
 
 wxWidgetImplType* wxWidgetImpl::CreateDisclosureTriangle( wxWindowMac* wxpeer,
                                     wxWindowMac* WXUNUSED(parent),
-                                    wxWindowID WXUNUSED(id),
+                                    wxWindowID WXUNUSED(winid),
                                     const wxString& label,
                                     const wxPoint& pos,
                                     const wxSize& size,
-                                    long WXUNUSED(style),
+                                    long style,
                                     long WXUNUSED(extraStyle))
 {
     NSRect r = wxOSXGetFrameForControl( wxpeer, pos , size ) ;
     wxDisclosureNSButton* v = [[wxDisclosureNSButton alloc] initWithFrame:r];
-    [v setTitle:wxCFStringRef( label).AsNSString()];
-    wxDisclosureTriangleCocoaImpl* c = new wxDisclosureTriangleCocoaImpl( wxpeer, v );
-    return c;
+    if ( !label.empty() )
+        [v setTitle:wxCFStringRef(label).AsNSString()];
+
+    SetBezelStyleFromBorderFlags(v, style);
+
+    return new wxDisclosureTriangleCocoaImpl( wxpeer, v );
 }