datadiode

WinMerge 2011 uses a less old version of Diffutils (v3.6).

I don't know, but one possible reason is to avoid GPLv3.

I cannot confirm this issue. Regexp "=>wwv_flow_api.id\(\d+\)" seems to yield expected results. Since it might depend on settings, can you share the outcome of _Help_ → _Configuration_?

From your screenshot it occurs to me that line filters might be disabled altogether, as per the option at the top of the _Filters_ dialog: 

Can you share the involved files? Does the situation change when you uncheck the other line filters?

Can you share your LineFilters.ini? Although I lost focus on this project, I'd like to understand and fix the bug.

Oops, I didn't remember that line filters entered through GUI are stored in the Windows registry. Can you export them to a file? 

(Un)fortunately, the 0.2011.211.182 build is not among released ones, and meanwhile disappeared from AppVeyor. This is what I get with your exact set of line filters, using [this fresh build](https://ci.appveyor.com/project/datadiode/winmerge2011/build/artifacts)...

Thanks for your bug report. You may want to try the CI build at https://ci.appveyor.com/project/datadiode/winmerge2011/builds/38108231/artifacts.