FIX: combox can not pop if hide with entry keyevent

Change-Id: I0b86ebadd524eafb69ba810f7a1b899ecb25914c

src/slic3r/GUI/Widgets/ComboBox.cpp

@@ -236,7 +236,7 @@ void ComboBox::keyDown(wxKeyEvent& event)
         case WXK_RETURN:
         case WXK_SPACE:
             if (drop_down) {
-                drop.Hide();
+                drop.DismissAndNotify();
             } else if (drop.HasDismissLongTime()) {
                 drop.autoPosition();
                 drop_down = true;