Creates a sizer with standard buttons. flags is a bit list of the following flags: wxOK, wxCANCEL, wxYES, wxNO, wxHELP, wxNO_DEFAULT.
Closes a modal dialog. ret is the value returned by show_modal().
Opens a modal dialog, which grabs the focus, and does not release it until it is closed. This is the way to use a dialog to get user input. See also end_modal.