After changing data in one field, and then undoing that change (Ctrl-Z) the screen scrolls and new, unrelated files become selected.
I think that the problem occurs when one field (e.g. Title) has its sort order specified (using "Customise Columns..." and "Sort On") to depend on a different field (e.g. TitleSortOrder).
The problem seems to arise in cases where, in this example, "Title" is selected as the currently-active sort field, several files are selected and the data in their "TitleSortOrder" field is changed so as to make them out of sort order. No re-sort occurs immediately, but following this with an "Undo" triggers a re-sort, but the the file selection changes. However, there is some other factor involved, or I've got some part of it wrong, because I haven't been able to reproduce it by doing only these steps.
Sorry I don't have a precise step by step method of reproducing it, but I've seen it happen "in the wild" twice, and I was able to trigger it deliberately twice immediately after that. When I tried to pin it down, however, it stopped happening once I'd specified a different sort column, then the first one again.
As far as I can tell, the displayed data is itself correct, it's only the selection status that changes, so it's not quite as critical as some of the other "undo-related" issues.
Sorry this is a little vague - there may or may not be enough information here to identify the issue in the code. I'll post more details as/if I find them.
(BTW, in case anyone thinks I'm doing a lot of "undo" operations - it's not just that I make a lot of mistakes - I'm testing out some Action Groups for manipulating names. I'll release them when they're done. On the other hand, I do make a lot of mistakes, too... )
(Keep up the good work, Florian!)