Dual head displays

[Ian Dean <ian.d.dean(at)baesystems.com>]

Hi,
 We have been successfully using two X-window displays (on separate
terminals each with its own IP address) on a DEC??? Alpha running
OpenVMS 7.1 and using IDL 5.4. The way this is achieved is as follows:

 $ Set display/create/node=ABC/transport=tcpip Display_1

The above VMS command is used to define a second display on "Display_1"

PRO Head_2
    Base_1 = WIDGET_BASE(XSIZE = 100, YSIZE = 200) ; Base on default
screen
    Base_2 = WIDGET_BASE(DISPLAY = 'Display_1', $
        XSIZE = 100, YSIZE = 200)                  ; Base on second
screen
    Text_1 = WIDGET_TEXT(Base_1, VALUE = 'Rubbish')
    Text_2 = WIDGET_TEXT(Base_2, VALUE = 'More Rubbish')
    WIDGET_CONTROL, Base_1, /REALIZE
    WIDGET_CONTROL, Base_2, /REALIZE
END

This has been working successfully for some years, but up until now,
only text has been displayed on the second terminal and graphics+text on
the first terminal.
However, we now have a requirement to display graphics on the second
screen. In order to achieve this, the following line was added before
line 7 above:

    Draw_2 = WIDGET_DRAW(Base_2, XSIZE = 50, YSIZE = 50)

This causes the following error to be reported:

%WIDGET_DRAW: Non-default Display not supported for old graphics.

What exactly does this mean?
Is OLD graphics direct graphics?
How can I achieve the desired draw widget on the second terminal?

The above is obviously a cut-down version of the problem. The actual
software exhibits even more strange effects:

1) When the package is run using the run command, IDL crashes with an
access violation - not very helpful.

2) When stepping through the software, IDL appears to pass the point
where the crash happens.

3) AT the point when trying to create the draw widget, IDL does not
report any errors, but the X windows system does as follows.

    %X windows protocol error: BadDrawable (invalid Pixmap or Window
parameter)

There must be someone out there who has achieved the effect we are
looking for. I have e-mailed RSI, but am not holding my breath for a
quick (or even useful) reply.

Regards,
 Ian