[BUG} Phantom line added when identical blocks of text pasted

[dcog989]

Reproduce:

1. New Document
2. paste a multi-line block of text in 1st pane
3. focus 2nd pane by clicking approx. centre
4. paste identical block in 2nd pane
5. result = a 'phantom' line is added to the 2nd pane

Note: problem does not occur if 2nd pane is focused by clicking on top or bottom line.

Version: 2.16.47b

[sdottaka]

Hmm I haven't been able to reproduce this issue so far...

[dcog989]

It happens every time for me - with any block of text. Maybe try my settings?

Winmerge-registry-20250331-174417.zip

[sdottaka]

Thank you for attaching the file.
This problem was reproduced when I enabled Automatic rescan in the Editor → Compare/Merge section of the Options window.

[dcog989]

Confirmed. I just disabled that and it removes the color coding to show the 'missing' content in pane 2, so it forces the pasted content to always land on line 1.

Hopefully the fix is easy! :)

[sdottaka]

This issue has been fixed in commit bd281a8. Thank you for your report

[dcog989]

@sdottaka - would you consider creating a nightly branch so we can test changes before the production release?

[sdottaka]

If it is an x64 binary, there is a CI Build artifact.
You can download it from the following URL.
Note that these cannot be code signed, so Windows may block their execution.

https://ci.appveyor.com/project/sdottaka/winmerge/build/artifacts
https://github.com/WinMerge/winmerge/actions/runs/14254676436

[dcog989]

Excellent! I'll keep an eye on those in future. Thank you!

[dcog989]

I just tried winmerge-2.16.47-9c4970d98-x64-exe.zip. The original problem is fixed in some cases, but not others. Results:

Case 1

If I paste content with length >50% of viewport that ends with a blank line anywhere other than the top line in pane 2, then the content in pane 2 is scrolled out of the view window:

Case 2

If I paste content without a blank line at end, then the original problem occurs:

Case 3

So the problem is fixed with content length <51% of viewport. I notice that 'line 1' will jump from top to bottom of pane 2 depending on if pane 1 content ends with a blank line:

versus:

My settings again (I may have changed something from last time) -

WinMerge-registry-20250405-181604.zip

Note - using 4K monitor (3840x2160) @150% scale

[sdottaka]

Thank you for reporting...

I was able to reproduce Case 1, but it is probably the same problem as #296, so I think it will be difficult to deal with immediately.

As for Case 2, I understand that you think this is strange behavior, but I think it is not so bad behavior. For example, the first line in the right pane is an empty line without a line break, but if the first line contains the string AAA without a line break, when you paste it on the second line, would you expect the string to be pasted immediately after AAA on the first line? Or would you expect AAA on the first line to be pasted on the second line with a line break? I expect the latter. The same applies if the first line is an empty line.

As for Case 3, I don't think it is a problem. In the example of the first image, the first line on the right does not match any line on the left, so it is displayed like this, but in the second image, the first line on the right matches the last line on the left, so it is displayed like this.

[dcog989]

Thanks for the reply.

• Case 1 - OK, understood. It's solved by scrolling and then pane 1 and 2 are synced.
• Case 2 - I think I understand your argument, but it still seems 'wrong' that we can paste identical blocks of text and the result = different??? Either way, it is a small issue only involving white space
• Case 3 - OK, understood. Although, it seemed to me that if line 1 was always at top of viewport, then it would solve some of the other problems - on the basis of not understanding the code at all!! :)

👍

[dcog989]

Hi. I would just like to have another go at this as it is a constant nuisance for me and seems like there is a solution - i.e. just make the second pain totally void rather than containing a blank line (CR / LF). That blank line is causing the false report of a line difference with identical documents (or adding the line difference even though the pasted content does not have a leading blank line).

E.g.:

I have just pasted content in to first panel and it auto scrolls to bottom. At the top of the second panel is a blank line (Line 1).

If I now focus the second panel by clicking anywhere in the viewable area then paste the identical content, it is added after the 'phantom' blank line.

If the 'phantom line' was not created, this problem would be solved? I can't see any downside???