wxwidgets.cfg: Added support for more interfaces

cfg/wxwidgets.cfg

@@ -5539,6 +5539,18 @@
       <not-bool/>
     </arg>
   </function>
+  <!-- virtual wxString wxListbox::GetString (unsigned int n) const-->
+  <function name="wxListbox::GetString">
+    <noreturn>false</noreturn>
+    <leak-ignore/>
+    <use-retval/>
+    <returnValue type="wxString"/>
+    <arg nr="1" direction="in">
+      <valid>0:</valid>
+      <not-uninit/>
+      <not-bool/>
+    </arg>
+  </function>
   <!--virtual int wxListBox::GetSelection(void) const-->
   <function name="wxListBox::GetSelection">
     <noreturn>false</noreturn>