When "File" menu is chosen, ECL Watch collects info on all files and them show the first N files in some order (latest created?).
I believe that no one really ever "browses" the files: the first thing anyone does when going to "File" is invoking "Filter Set" dialog to define the files that are of interest.
Collecting info on all files can take quite a time, so – after opening filter dialog – the message "The number of files returned is too large..." may appear after user have started typing the filtering criteria, which shifts the dialog's focus, and typing is partially wasted. In addition, browser sometimes just freezes during opening filter dialog, and the only remedy is to open another tab/window.
I would suggest to consider the following changes:
1. The message "The number of files returned is too large..." is not informative, since this is always the case in our circumstances. What's more, the message stays in the filter dialog forever, which is hardly of any use. At the very least I'd want it to not to change the layout of the filter dialog, but perhaps removing it for good would be even better.
Or, perhaps, placing a warning "... environment has more than ... files" in the status string would be a reasonable alternative.
2. Maybe returning first, say, thousand files would be good enough, instead of returning an ordered list? "First" here is whatever natural order there is available for fetching without collecting info on all files, even if random. Again, I'm quite certain that one almost never browse for files, but rather searches for them.