There are some debates about IT products which are far more like religious arguments rather than technical discussions because there really are no right or wrong answers, just opinions.
Obvious examples are the two button "PC Mouse" vs. the single button "Mac Mouse", coding using "Multi Threading" vs "Multi Process" techniques, using images in GIF, JPG or PNG format or perhaps the ultimate in cosmetic comparisons, the Black Thinkpad vs the White Macbook
One such debate has revolved around what key should be used to refresh a view or page or in the case of a mail client, check for new mail. As with most things in the PC Software world, there has never been a standard for such things. Each developer does what they think best. However, over time "De facto" standards sometimes emerge. In the case of the refresh key, it became the key F9 since this was what was used by Lotus 123, the dominant application at the beginning of the PC age. As 123 was gradually overtaken by Microsoft Excel it also used F9 for refreshing. Lotus Notes has followed this convention and has used F9 for refresh for nearly 20 years.
However, in more recent years Microsoft started using the F5 key for refresh in some (but by no means all) applications, most notably Windows Explorer and Internet Explorer. Confusingly Microsoft Outlook 2003 uses F5 to refresh the view but F9 to check for new mail.
So what to do with Lotus Notes? Clearly it wouldn't be fair on our current customers to change the behaviour of F9, but on the other hand many new Lotus Notes users expect refresh to be F5 because of their experience with Microsoft Windows. So in version 8.5 of Lotus Notes either F5 or F9 can be used to refresh a view and check for new mail. It also means that F5 can be used in Symphony Presentations to start a slide show. A very pragmatic solution I think.