Here's a description of the steps i did and a small bug i noticed in the "New Records" column in the Groups tab.
In the Server Options screen, i have one server selected but due to incomplete posts i was getting, i have set the "Header overlap" field to 5000, just to be sure no incompletes are generated (as very well instructed by Quade in this thread).
- Select a group but don't doubleclick it.
- Download all (or new only, i don't think it matters) headers for it.
- Then double click the group in order to open a new tab for it. The newest headers are re-downloaded but when the header-download process finishes, if there are no new posts, the "New Records" column value is not set to 0. Closing and reopening NB and repeating the process has the same result. If you go to the Server Options and set the "Header overlap" field to 0 and repeat the process, the "New Records" column is normally set to 0.
P.S.: I just noticed that if you manually re-download the Latest Headers X times and you initially had a value of Y in the "New Records" column, after the X times you get a vaule of X*Y in the "New Records" column (that is, if you have a "Header overlap" <> 0 value). If you just close and re-open the group tab X times though (by double-clicking on it), you always get Y in "New Records" column.