Open Navigation attachment panel with Reader 7.0

The menu commands for displaying the navigation panels are really toggles. Select it once and the panel appears, select it again and it dissappears. There is no way from JS to know whether the panel is shown or hidden.

There are also other problems, in Acrobat 8 the menu items that can be run from a document are restricted with a list in the registry. Although I think the view navigation panels items are available, but I'm not sure.

And finally, there is the problem you are seeing, which is that the internal menu item name for the showing and hiding the Attachments Panel is different between Acrobat 8 and Acrobat 7.

But you could use a script to fix this problem:

if(app.viewerVersion >= 8)
app.execMenuItem("ShowHideFileAttachement");
else
app.execMenuItem("ShowHideAttachements");

Great tip, thomp!

Just FYI, there was a typo in thomp's reply ("Attachements"). The following works for Acrobat version 9.1:

1) Advanced->Document Processing->Document JavaScripts
2) Type "ToggleAttachmentsPane", click Add
3) Delete this text:

function ToggleAttachmentsPane() { }

and replace with

if(app.viewerVersion >= 8)
app.execMenuItem("ShowHideFileAttachment");

Note that some menu actions will cause the document to get reloaded, and thus the attachments pane will toggle back off (for instance, if you go back a second time to Advanced->Document Processing->Document JavaScripts and close). But at least this will work for the common user of Acrobat Reader.

I am trying to use
if(app.viewerVersion >= 8)
app.execMenuItem("ShowHideFileAttachement");
else
app.execMenuItem("ShowHideAttachements");

but get
InvalidArgsError: Invalid arguments.
App.execMenuItem:2:Link undefined:Mouse Up

Can anyone help please?

ps I have no idea about what jpjarosz is saying! and how it effects the code I am trying to use?

Things have changed since version 8. You can no longer call execMenuItem from a button directly.
It must be done through a trusted function, installed on the local machine.