Merge pull request conformal#32 from twstrike/gtk-assistant

Add support to GtkAssistant

gtk/gtk.go

@@ -1245,13 +1245,14 @@ func (v *Assistant) GetNPages() int {
 }
 
 // GetNthPage is a wrapper around gtk_assistant_get_nth_page().
-func (v *Assistant) GetNthPage(pageNum int) *Widget {
+func (v *Assistant) GetNthPage(pageNum int) (*Widget, error) {
 	c := C.gtk_assistant_get_nth_page(v.native(), C.gint(pageNum))
 	if c == nil {
-		return nil
+		return nil, fmt.Errorf("page %d is out of bounds", pageNum)
 	}
+
 	obj := wrapObject(unsafe.Pointer(c))
-	return wrapWidget(obj)
+	return wrapWidget(obj), nil
 }
 
 // PrependPage is a wrapper around gtk_assistant_prepend_page().
@@ -10376,6 +10377,7 @@ var WrapMap = map[string]WrapFn{
 	"GtkAccelGroup":          wrapAccelGroup,
 	"GtkAccelMao":            wrapAccelMap,
 	"GtkAdjustment":          wrapAdjustment,
+	"GtkAssistant":           wrapAssistant,
 	"GtkBin":                 wrapBin,
 	"GtkBox":                 wrapBox,
 	"GtkButton":              wrapButton,