T-SQL – Script all tables creation, contraints, indexes, keys and triggers

You can't.

The SSMS tab is named after the open file, not the contents of the window/file.
So if you have not saved it, it has no name to assign

SQL Server Management Objects SMO is your answer. You can use it to accomplish this task. Here is an example to generate Create Table Scripts.

    public string GetTableDescription(string pDatabaseName, string pSchemaName, string pTableName, string connectionString)
    {
        connectionString = ConnectionHelper.RemoveProviderFromConnectionString(connectionString);
        Server server = new Server(new ServerConnection(new SqlConnection(connectionString)));
        Database db = server.Databases[pDatabaseName];
        Table t = db.Tables[pTableName, pSchemaName];
        ScriptingOptions baseOptions = new ScriptingOptions();
        baseOptions.NoCollation = true;
        baseOptions.SchemaQualify = true;
        baseOptions.DriDefaults = true;
        baseOptions.IncludeHeaders = false;
        baseOptions.DriPrimaryKey = true;
        baseOptions.ExtendedProperties = true;
        //baseOptions.DriAll = true;
        //baseOptions.Indexes = true;
        //baseOptions.DriAllKeys = true;
        //baseOptions.SchemaQualifyForeignKeysReferences = true;
        baseOptions.EnforceScriptingOptions = true;
        StringCollection result = t.Script(baseOptions);
        return StringCreate(result);
    }