You could refresh any folder in Explorer, not just your desktop. It's not just about Active Desktop 'michaelt mentioned (which had a refresh, but I guess it was a different refresh, coming from IE and not explorer.exe), but - as 'UnoriginalGuy hinted - because Explorer could, and often did, go out of sync for various reasons. It didn't affect only networked drives, it happened equally well when you had enough many files in a folder (something must have been timing out) or your computer was overloaded. The most common case I recall - Explorer didn't automatically show files created by other programs, sometimes it didn't even show a folder or a file you created via context menu.
Actually, I'm pretty sure some of this still happens today, in particular I remember noticing on Vista/Win7 that Explorer sometimes doesn't immediately refresh the folder contents when there's a new file created by external application (e.g. a log file), and refresh/F5 is useful to get this file visible immediately.
Funny thing, per the phenomenon of operant conditioning, over the years of using Windows I learned to regularly refresh Explorer windows via F5 to ensure I always see what's really there, sometimes just for my own peace of mind.
An example of this: One thing that Windows versions up to at least 7 have always had issues with is that when you rename a file to be the same name with a slightly different case, say after changing an uppercase letter to a lowercase one, Explorer doesn't seem to pick up on the change until a refresh is manually triggered.
Oh, and here I always thought it just doesn't rename the file at all. NTFS is case-sensitive but Explorer is only case-preserving, so I thought it was just assuming I typed in the same name. When I wanted to change the case of a file name, I always renamed the file first to something else, eg. "Foo.txt" => "bar.txt" => "foo.txt". Thanks for the information :).
The most common use I have of the refresh feature is to observe the sizes of output files (e.g. logs) from a process to see their growth.
If you have a process that creates a file and then writes e.g. several KB to it every few seconds, without doing anything you'll just see the file created with a size of 0. Eventually it does move from 0 but if you want to see the current size you need to refresh.
I've still run into these quirks on 8.1, particularly when deleting files outside of the Desktop itself (e.g. through other programs/command line, maybe Explorer).
It is possible, although rare, for Windows Explorer to get out of sync with what exists on the file system or virtual filesystem(s). The refresh button re-acquires the data from the source and re-draws the result for the user.
For example, if you open a network share, delete a file using another machine that file might take between several seconds to a minute to disappear visually (although if you try to use the file you'll get an error and it will refresh removing it). You can alternatively use the refresh button to get an updated view instantly.
It is mostly useful with non-standard virtual file system services rather than the normal NTFS/FAT32 file systems Windows uses.
I've seen cases where windows explorer will arbitrarily decide to stop updating an entire folder tree for no apparent reason, at which point being able to push F5 suddenly becomes very handy. Of course, it doesn't help when I tell explorer to create a new folder which doesn't show up, thereby making it impossible to assign it a name until you refresh and then find the "New Folder" you just created.
All file notification systems tend to be somewhat race condition prone, or to lose events under some circumstances. Linux has a lot of different subsystems, none of which always work https://lwn.net/Articles/604686/
As you can see people have to come up with quirky workarounds to force refresh a folder on OS X, rather than just clicking a context menu button helpfully provided.
Others have created third party software to add it:
Both Windows and OS X fall out of sync for similar reasons: sometimes bugs, sometimes refreshing is slow/expensive so is done infrequently (e.g. over a network), and sometimes third party software providing "virtual" file system elements are terrible.
I don't really find the concept of a refresh button odd at all. But that's only because I've seen how many virtual file system providers these systems support and how quirky some of them are. If all they supported is native files on traditional file systems attached via reliable buses, then a refresh button wouldn't be required.
Huh, none of these show the workaround I've always used: create a new folder and delete it. That's been my "pseudo-refresh" for years, because it's relatively quick to type command-shift-n, command-delete.
Two other things that cause Finder to show stale data:
- change the icns file inside an app
- enable 'calculate all sizes', then delete a file in a subdirectory
There's no easy way to refresh due to the various levels of caching involved. Closing and reopening windows doesn't help. In the icns case, not even killing Finder helps. So I assume that even if Apple wasn't fundamentally opposed to a refresh button in the UI, it would be non-trivial to implement the back button.
Back in Windows 98 there was a feature called 'Active Desktop' that could use web pages as desktop wallpaper (or partial desktop wallpaper). It was intended to be an early version of desktop widgets like stock tickers. As these were basically web pages, you could refresh for the same reasons you might refresh in a web browser.
As you could execute javascript it was also possible to do things like change your desktop wallpaper when you resized or rotated your screen. But active desktop was never heavily used enough to have all the bugs in it sorted out - if you widget's javascript tried to display a message box you could trigger a crash, for example.
I assume that feature is gone now - but presumably you can still put files on the desktop, so presumably there's a refresh button in case you have some strange configuration like your desktop folder mounted from a network share.
Also it had horrible performance. Even without any active desktop content, just having it enabled was enough to make any desktop interaction painfully slow compared to having it disabled.
Like other people said, it is about refreshing the view for changes that didn't trigger an automatic refresh.
If you dig the details, behind the scenes an API called ReadDirectoryChangesW is called, which uses a notification-like system to report changes within a directory. However, that API is weird, so various types of changes are not correctly reported and explorer.exe is stuck with outdated data. The refresh forces it to update the view.
Disclaimer: I've had to use that API recently to code a simple python file monitor in Windows. https://github.com/gusmd/vigil.py in case anyone is interested.
If number of bytes transferred is zero, the buffer was too small to provide detailed information on all the changes that occurred in the directory or subtree. In this case, you should compute the changes by enumerating the directory or subtree.
I suppose that's the case when Explorer gives up, because for this to work it would require keeping a copy of all the directory contents to compare with, and "enumerating" would be unacceptably slow.
To add to the comments about file listings not refreshing, note that the desktop is just a fancy-looking Explorer file listing widget ("control" in Windows-speak).
It's also worth noting that the standard File Open and File Save dialogs are full-fledged File Explorer windows too.
I make use of this all the time. For example, I often want to open the same file in two different editors. So in the editor where I have the file already open, I do a Save As to get into the dialog, then simply drag the file directly from that dialog into the other editor, and close the dialog without saving.
Alt+D also works the same in these dialogs as an Explorer window, so a quick way to copy the current file's directory to the clipboard is to do a Save As, Alt+D, Ctrl+C, Esc.
Or to open a standalone File Explorer window somewhere in my current project: Save As, right-click the folder in the Save As dialog, and Open in New Window.
All kinds of nice shortcuts like this are available once you realize that the File dialogs are Explorer windows.
It isn't. Sometimes you have a folder open and another program creates a file in it; Explorer may not update your display for another 30 seconds or so, so you can force the update with refresh.
If you ever work on two computers over a shared network drive with Macs working in the exact same folder you'll immediately know the answer to this question ;) I don't understand why every system doesn't have one.
I use it when I do a Subversion update. TortoiseSVN puts a red icon on non-current folders and a green icon on up-to-date folders. Sometimes the icon doesn't change color when you update though, so you have to refresh.
To keep the non-technophiles occupied while they wait for their external device to be detected, and to soothe them by giving them something to do (repeatedly) to "speed up" their ageing computer.
You are getting a lot of down votes, but the truth is that this behavior is very common in some cultures, and not all of HN may have seen it before.
When I get impatient I just swirl the mouse in a small counter-clockwise circle, but I have seen others do the rapid right click, refresh sequence. It was mostly Asian computer users[0], and some of them had practiced it enough that they would do this 3-4 times per second while waiting for the computer to react.
[0] I first noticed this in Iraq, but the Chinese students at school do the same thing.
In the past when CRT monitors were in usage,the ui needs to be painted on the screen.The crt technology refreshes screen so that pixels can work properly.If they are not refreshed,then some pixels become 'dead'.
Actually, I'm pretty sure some of this still happens today, in particular I remember noticing on Vista/Win7 that Explorer sometimes doesn't immediately refresh the folder contents when there's a new file created by external application (e.g. a log file), and refresh/F5 is useful to get this file visible immediately.
Funny thing, per the phenomenon of operant conditioning, over the years of using Windows I learned to regularly refresh Explorer windows via F5 to ensure I always see what's really there, sometimes just for my own peace of mind.