It looked liked any other code review process. We used Perforce. So a custom tool was integrated into Perforce's visual tool such that you could right-click a changelist and submit it for code review. The changelist would be shelved, and then LabVIEW's diff tool (lvcompare.exe) would be used to create screenshots of all the changes (actually, some custom tools may have done this in tandem with or as a replacement of the diff tool). These screenshots, with a before and after comparison, were uploaded to a code review web server (I forgot the tool used), where comments could be made on the code. You could even annotate the screenshots with little rectangles that highlighted what a comment was referring to. Once the comments were resolved, the code would be submitted and the changelist number logged with the review. This is based off of memory, so some details may be wrong.
This is important because it shows that such things can exist. So the common complaint is more about people forgetting that text-based code review tools originally didn't exist and were built. It's just that the visual ones need to be built and/or improved. Perforce makes this easier than git in my opinion because it is more scriptable and has a nice API. Perforce is also built to handle binary files, which is also better than git's design which is built around the assumption that everything is text.
I think there's a lot of nice features to be had in visual programming languages with visual compares. Like I said in another comment, I view text-based programming as a sort of 1.5 dimensional problem, and I think that makes diff tools rather limited. If you change things in a certain way, many diff tools will just say you completely removed a block and then added a new one, when all you did was re-arrange some stuff, and there's actually a lot of shared, unchanged code between the before and after blocks. So it's not like text-based tools don't have issues.
This is important because it shows that such things can exist. So the common complaint is more about people forgetting that text-based code review tools originally didn't exist and were built. It's just that the visual ones need to be built and/or improved. Perforce makes this easier than git in my opinion because it is more scriptable and has a nice API. Perforce is also built to handle binary files, which is also better than git's design which is built around the assumption that everything is text.
I think there's a lot of nice features to be had in visual programming languages with visual compares. Like I said in another comment, I view text-based programming as a sort of 1.5 dimensional problem, and I think that makes diff tools rather limited. If you change things in a certain way, many diff tools will just say you completely removed a block and then added a new one, when all you did was re-arrange some stuff, and there's actually a lot of shared, unchanged code between the before and after blocks. So it's not like text-based tools don't have issues.