Hover for rows in thread pane

[Vipin Gokhale]

In Netscape 4.x I get a little popup box when pointer hovers over, say,
subject column in thread pane. This popup will show up, for example, if
pointer hovers over the folder name in the folder list pane. I do not
get this in Netscape 6.1 or Mozilla 0.9.3. Is this already a known bug ?

Thanks,
Vipin