public OnPlayerConnect(playerid) {
    return ShowPlayerDialog(playerid, 1, DIALOG_STYLE_MSGBOX, "Title : Rules", "List : Rules", "Button 1", "Button 2");
}

public OnDialogResponse(playerid, dialogid, response, listitem, inputtext[])
{
    switch(dialogid) {
        case 1: {
            if( !response ) {
                SendClientMessage(playerid, -1, "You did not accept the rules.");
            }
            else {
                SendClientMessage(playerid, -1, "You accepted the rules.");
            }
        }
    }
    return true;
}