Redone (generic) wxComboCtrl background painting and handling. The 'actual' wxWindow background colour is now largely ignored and overridden to refer the text-area's background colour instead (as is usually the case with controls like this). Base 'transparent' background is now only painted when double-buffered rendering is required, and otherwise delegated to the system, as appropriate. This should significantly improve control's appearance and compliancy with GTK+ and OS X themes and custom backgrounds.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67255 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/generic/combo.h

@@ -31,6 +31,8 @@
 
 #endif
 
+#include "wx/dcbuffer.h"
+
 extern WXDLLIMPEXP_DATA_CORE(const char) wxComboBoxNameStr[];
 
 class WXDLLIMPEXP_CORE wxGenericComboCtrl : public wxComboCtrlBase
@@ -96,6 +98,21 @@ protected:
     virtual WXHWND GetEditHWND() const { return NULL; }
 #endif
 
+    // For better transparent background rendering
+    virtual bool HasTransparentBackground()
+    {
+        #if wxALWAYS_NATIVE_DOUBLE_BUFFER
+          #ifdef __WXGTK__
+            // Sanity check for GTK+
+            return IsDoubleBuffered();
+          #else
+            return true;
+          #endif
+        #else
+            return false;
+        #endif
+    }
+
     // Mandatory virtuals
     virtual void OnResize();