This option would add synchronization of file selection in dual lister, ie. selecting a file in source panel would select the same file in the other panel.
Such an option can be useful when browsing files using two different views at the same time, fe. image thumbnails and details. It can also be used, in vertical panel alignment, to display twice the number of columns for a file, in comparison to what can be displayed in one panel (more information visible).
X.
Have you tried using Select SOURCETODEST ? It's not quite the same but I find it works well for this kind of thing (and comparing different versions of files in particular).
But, as I understand, it is supposed to be triggered manually (button/hotkey) after selecting a file- and this generally defeats the whole purpose.
Or are action triggers avaliable in DOpus???
X.
It's a manual thing.
With your idea you presumably would also want scrolling to be kept in sync. How would that work with different numbers of files in the two sides, or in modes where items are different heights? Or would the scrolling only be updated when something was selected, to ensure that the last selected item was visible in both sides (if it exists in both sides)?
Yes, synchronous scrolling would be necessary.
I think that child panel should keep selected element at the same, relative to height, place that in master panel. This would allow easy checking up file data at the other panel. So that if I select element that is 25% from panel top, the other panels scrolls so, that the element inside it is also approximately 25% from the top.
Another approach could be "scroll just to make visible", where child panel scrolls just as much as to make appropriate element visible.
Another approach may be a mix of the two, where elements' positions are synchronized only when performing scrolling required to make an element visible.
If a panel displays whole directory contents, scrolling in that panel is not performed.
X.
So if nothing is selected then the scrolling isn't kept in sync? Or, if it is, how do you choose which items in the other list should be kept visible? Maybe if you are scrolling downwards then you find the last item in the scrolled list that is visible in the other list and make it visible in the other list. If scrolling up you look for the first item.
What if you select something and then scroll, does the other side continue to focus on the (most recently) selected item, or does it scroll the same as when nothing is selected?
It's definitely an interesting idea, if it can be implemented in a good way.
My idea is about selected files and my concept evolves around that.
It can be expanded to 'scroll-synchronizing' but it's a bit of another idea.
If nothing is being selected in file list panel, nothing is synchronized. User needs to select an item to make panels synchronize. This allows for free navigation using scrollbars, tree or buttons, while still retaining the functionality of NavFileLock. Generally, synchronization is considered by the application at the moment of selecting an item in file list (be it the only item or one of multiple selected items).
In my concept no scroll is performed when file list fits completely into panel, but it can also be changed (so that fe. lower half of file list is empty, while there are still items above first visible item).
As for ScrollLock, we can treat setting an item as first visible item of a panel (as a result of any action, fe. scrolling) as selecting it and then using logic for NavFileLock.
I think these two could live together with no problems, provided that there is option to select NavFileLock or ScrollLock priority (or inventing some smart interaction between them).
I think also that an interesting case to consider is two different directories in file panels.
X.
Quite an old thread, but I'm looking for something similar.
I'd love to be able to either set Scroll lock on my keyboard and/or set the NavLock in the dual lister, and I get synchronized scrolling.
The file selection is also a nifty idea.
I'm thinking about submitting this as a feature request, but I was wondering if you had already done so, Xyzzy, or if anybody has more thoughts on this?
Ta,
Anakha
Even if he has submitted it - go ahead... strength in number 
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I can say that in most EVERY case where I would enable NAVLOCK to begin with, I'd ALSO want synced scrolling and automatic file selection to take place in both displays.
I have submitted a feature request with GP Software. Let's see what the come up with 
There isn't something new regarding this?
No changes in this area yet, AFAIK.
I think we've "talked" before about how it might theoretically work... at least, insofar as the implied need for synced scrolling.
What I can say is that most every 'diff' tool I've used such as WinMerge, UltraCompare, or Beyond Compare (I stick with Araxis Merge myself, to which there's no "comparison" in my opinion - pun intended 
) seem to have this nailed where the sync of the scrolling is mostly "relative" to the general vertical orientation and length, and tends to "snap" a bit to show the beginning and ends of significant areas of difference to the center of the display. Otherwise, it just tends to scroll entirely relative to vertical when left/right are COMPLETELY out of whack...
I use Beyond Compare these days and it seems to insert blank items into each list so that the common items stay in sync. That seems like a good way to do it to me.
I saw another topic dealing about that, and as I wanted to ask the same question, here I am!
I see most of the things I could tell are already written in here, so I won't say that much more about it....
Just 2 things:
It would be really, really useful (strength in numbers as Steje says
My view on how it would be like is that the 2 panes would be kept in sync all the time, and for files which are not present on one side, a blank could be left (or maybe displaying a shadow of the file from the opposite side... with strikedthrough text or something similar)
oh, and I forgot, it would also be really usefull to be able to assign a shortcut or a button to move to the next difference when folders are compared.
And as an extension to that, also being able to display only the files which aren't synchronised (or maybe being able to expand the window telling the number of files which aren't synchronised to see all the concerned files)