You have two windows? Why? I always work in tabs, which can be put side by side in one Indesign window.
But scrolling both at once is not possible, because no matter if window or tab, only one has focus.
As said - you need to be focused on one Window/Tab to allow the scrolling.
What you could do is a make a PDF of both.
Then in Acrobat Professional you can run a "Comparison" and you can select to have them side by side on screen.
Then you can scroll the PDFs at the same time.
Hope that Helps.
Well, by saying "window" I meant the document itself. I just do it like you say: two documents next to each other and compare.
And yes, it's true, only one document can have the focus. But with "Application Frame" enabled, you are able to see e.g. two documents, who are in the front within each split screen, at the same time.
The FRONT RIGHT doc has the focus, the FRONT LEFT does not, but it is visible as it is in the front layer of the left split screen.
So, (theoretically, from a programmer's point of view) it would be possible to let InDesign scroll in both documents: all documents that are in the first tab layer (= visible) would then scroll a page, regardless if one has the focus or not. I can understand that this is not yet part of the software, but for people who need to compare and alter documents with copy and paste a lot, it would be a great help.
Thank you for the PDF idea. I know that already and use it as well. But it's not only comparing two docs, it's more altering one (older) doc according to one (newer) doc in various languages, e.g. manuals etc.
This post is in German. Use a translation tool to read about it.
You could use keyboard shortcuts assigned for the scripts to scroll simultaniously all windows from different documents. Should work in InDesign CS4 and also above.
Direct download link for the scripts:
WOW! This is really cool! Thank you VERY much! Vielen Dank, Uwe!
The only (minor) flaw is, that this works with double page spread only. So no single page scrolling. But anyway: This Is Great! (…did I say that already?)