diff --git a/docs/changes.txt b/docs/changes.txt
index faa63680f9..c75de4e0b2 100644
--- a/docs/changes.txt
+++ b/docs/changes.txt
@@ -213,6 +213,7 @@ wxOSX:
 - Add a native implementation for clearing bitmap/window wxGraphicsContexts
 - wxiOS now needs a minimum of iOS 9 for deployment
 - Fix handling CTM in wxGraphicsContext::SeTransform and GetTransform().
+- Allow turning on/off opacity selector in wxColourDialog.
 
 Unix:
 
diff --git a/interface/wx/colourdata.h b/interface/wx/colourdata.h
index 0b1dea908f..a078ef4692 100644
--- a/interface/wx/colourdata.h
+++ b/interface/wx/colourdata.h
@@ -46,6 +46,16 @@ public:
     */
     bool GetChooseFull() const;
 
+    /**
+        Indicates whether the colour dialog will display alpha values
+        and an opacity selector. It is meaningful under wxGTK, wxOSX
+        and with regards to generic colour dialog.
+
+        The default value is @false, except wxOSX where it is @true (for
+        the sake of backward compatibility).
+    */
+    bool GetChooseAlpha() const;
+
     /**
         Gets the current colour associated with the colour dialog.
 
@@ -72,6 +82,16 @@ public:
     */
     void SetChooseFull(bool flag);
 
+    /**
+        Tells the colour dialog to show alpha values and an opacity selector
+        (slider). Currently it has effect under wxGTK, wxOSX and for generic
+        colour dialog.
+
+        The default value is @false, except wxOSX where it is @true for
+        backward compatibility.
+    */
+    void SetChooseAlpha(bool flag);
+
     /**
         Sets the default colour for the colour dialog.
 
diff --git a/src/common/colourdata.cpp b/src/common/colourdata.cpp
index 3ad774195f..2c2dddabf1 100644
--- a/src/common/colourdata.cpp
+++ b/src/common/colourdata.cpp
@@ -25,7 +25,14 @@ wxIMPLEMENT_DYNAMIC_CLASS(wxColourData, wxObject);
 wxColourData::wxColourData()
 {
     m_chooseFull = false;
+#ifdef __WXOSX__
+    // Under OSX, legacy wxColourDialog had opacity selector
+    // (slider) always enabled, so for backward compatibilty
+    // we should tell the dialog to enable it by default.
+    m_chooseAlpha = true;
+#else
     m_chooseAlpha = false;
+#endif // __WXOSX__ / !__WXOSX__
     m_dataColour.Set(0,0,0);
     // m_custColours are wxNullColours initially
 }
diff --git a/src/osx/carbon/colordlgosx.mm b/src/osx/carbon/colordlgosx.mm
index 495584f7f1..6a63af1197 100644
--- a/src/osx/carbon/colordlgosx.mm
+++ b/src/osx/carbon/colordlgosx.mm
@@ -106,7 +106,7 @@ bool wxColourDialog::Create(wxWindow *parent, wxColourData *data)
     NSAutoreleasePool *thePool;
     thePool = [[NSAutoreleasePool alloc] init];
 
-    [[NSColorPanel sharedColorPanel] setShowsAlpha:YES];
+    [[NSColorPanel sharedColorPanel] setShowsAlpha:m_colourData.GetChooseAlpha() ? YES : NO];
     if(m_colourData.GetColour().IsOk())
         [[NSColorPanel sharedColorPanel] setColor:m_colourData.GetColour().OSXGetNSColor()];
     else