Fix background colour returned by wxTextCtrl::GetStyle() in wxMSW

Don't return the background colour unless it's really set, otherwise we
returned black background even if it was never changed.

docs/changes.txt

@@ -94,6 +94,7 @@ wxMSW:
 - Fix crash when using wxCHMHelpController() in 64 bit builds (Xlord2).
 - Fix MDI menu display after failure to create a child frame (troelsk).
 - Fix wxScreenDC::GetSize() with multiple monitors (iwbnwif).
+- Fix background colour returned by wxTextCtrl::GetStyle() (Andreas Falkenhahn).
 
 wxOSX:
 

src/msw/textctrl.cpp

@@ -3054,9 +3054,14 @@ bool wxTextCtrl::GetStyle(long position, wxTextAttr& style)
 #if wxUSE_RICHEDIT2
     if ( m_verRichEdit != 1 )
     {
-        // cf.dwMask |= CFM_BACKCOLOR;
+        // Notice that, surprisingly, CFM_BACKCOLOR is still set in the mask
+        // even when CFE_AUTOBACKCOLOR is set in the effects, indicating that
+        // the background colour is not used.
+        if ( !(cf.dwEffects & CFE_AUTOBACKCOLOR) && (cf.dwMask & CFM_BACKCOLOR) )
+        {
             style.SetBackgroundColour(wxColour(cf.crBackColor));
         }
+    }
 #endif // wxUSE_RICHEDIT2
 
     // now get the paragraph formatting