Bug 499234

Summary: Problem with The Regular Expression for The Lookback Function (?<=pattern)
Product: [Applications] krename Reporter: Michael Jenkins <ukmjenkins>
Component: generalAssignee: Heiko Becker <heiko.becker>
Status: REPORTED ---    
Severity: normal CC: ukmjenkins
Priority: NOR    
Version First Reported In: 5.0.1   
Target Milestone: ---   
Platform: Ubuntu   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description Michael Jenkins 2025-01-28 07:05:30 UTC 
SUMMARY

I have a file with the filename:
00 0000 00.txt

(1) For Find and Replace,
I can type, the lookahaed function:
Find = \s(?=\d(4})
Replace = X

So that, when I select "Okay",
The Proposed Filename correctly appears:
00X0000 00.txt

(2) For Find and Replace,
I can type, the lookback function:
Find = (?<=\d(4})\s
Replace = X

However, when I select "Okay",
The Proposed Filename incorrectly appears:
00 0000 00.txt

When, the correct result would  be:
00 0000X00.txt

STEPS TO REPRODUCE

OBSERVED RESULT

The lookback function appears to not work.
I have tested the lookahead and lookback functions, several times.
The lookahead function always works.
The lookback function never works.

Please Help.

EXPECTED RESULT

SOFTWARE/OS VERSIONS
Xubuntu 22.04 LTS

ADDITIONAL INFORMATION
7am Tuesday 28 2025.