Thx K
Yes, thats more what I was originally thinking.  I rarely (if ever) use DOWNLOAD DOCUMENT.  Early on, I was thinking I'd make a report with the Document inside it, then DISPLAY DOCUMENT.  Less than ideal.  So I asked here thinking I was missing something obvious - which I was.
I tried it, but I like it my original way... for these reasons:
1) Even on my machine, it downloaded the file, requiring a click to open it.  Would hate to hassle with a group of users and make them install the viewer plugin (or whatever settings allow it to auto display)
2) Opened in new tab - vs. Popup.  I actually like the popup in this case to briefly view the PDF.
My Code (with help from John):
var theID = parser.m_highlightedRow.refValue.split(":")[1];
AwareApp.viewDocument ('ReqLines', theID , 'ReqAttachment')
--> JaymerTip Display PDF directly from Grid