Add "hint" property support to XRC for wxComboBox too

It supports hints, as any/most wxTextEntry-derived classes.

docs/changes.txt

@@ -100,6 +100,7 @@ All (GUI):
 - Make wxRibbonButtonBar buttons more customizable (Max Maisel).
 - Add wxHtmlEasyPrinting::SetPromptMode() (pavel-t).
 - Fix possible infinite loop in wxHtmlWindow layout (trivia21).
+- Add "hint" property support to XRC for wxComboBox and wxSearchCtrl.
 
 wxGTK:
 

misc/schema/xrc_schema.rnc

@@ -829,6 +829,7 @@ wxComboBox =
         stdWindowProperties &
         [xrc:p="o"] element selection {_, t_integer }* &
         [xrc:p="o"] element value     {_, t_string }* &
+        [xrc:p="o"] element hint      {_, t_text }* &
         element content {
             platform,
             element item {_, t_text }*

src/xrc/xh_combo.cpp

@@ -67,6 +67,10 @@ wxObject *wxComboBoxXmlHandler::DoCreateResource()
 
         SetupWindow(control);
 
+        const wxString hint = GetText(wxS("hint"));
+        if ( !hint.empty() )
+            control->SetHint(hint);
+
         strList.Clear();    // dump the strings
 
         return control;