[JS CS3] Frontmost document/selection when other with same name?

Question

I have a few scripts used to perform various operations on the current selection in InDesign. Under normal circumstances these work fine, but I can't seem to reliably get the frontmost document/selection when there is another document open with the same name. Most references to the document and every reference to the selection I have tried so far will simply lead to the document which was most recently opened (and has the same name).
app.activeDocument.fullName always return the path to the most recently opened document of the same name, but app.documents[0].fullName will return the correct path. Trying to get the selection though will always return the selection of the most recently opened document of the same name, regardless of whether I try app.selection, app.activeDocument.selection or app.documents[0].selection. I have also tried with getElements()[0] appended to the document reference but it makes no difference.
My primary environment is still CS3 and the problem appears to be that it only references documents by name. Brief testing with CS5 indicates this has been solved by Adobe, presumably because it now refers to documents using an id by default. Haven't tried CS4 but since its document object does not have an id property I'd assume it will behave the same as CS3. Is there any way around this, or is the best I can do to detect the issue (a simple app.activeDocument != app.documents[0] comparison seems to work reliably) and refuse to run if encountered?

Answer 1

Welll...chances are the selected item will not be a valid ID in both documents of the same name. (I don't think ID's are globally unique, so that's not a guarantee -- but it's something you can check and only give an error if it happens to be that there is a collison).
So, get the transaction specifier of the selection:
app.activeWindow.selection[0].toSpecifier()
Result: /document[@name="u1.indd"]//text-frame[@id=211]
Then, iterate over app.documents to find the indexes of the documents with that name.
In my test, of course it is just zero and one.
Then, try to resolve the specifiers against those documents:
resolve("/document[0]//text-frame[@id=211]")
Result: [object TextFrame]
resolve("/document[1]//text-frame[@id=211]")
Error: Object is invalid
Since only doc 0 has a textFrame with id 211, you know it's doc 0 and you have a valid specifier.
I chose to adjust the specifier by hand, because I think that's probably the most general. The other choice would be to call app.documents[0].textFrames.itemByID(211), but then you would need to map "text-frame" to "textFrames" and that seems annoying and errorprone.