A folder only view could speed up loading Flat View mode when only
working with folders.
You can already set a filter to Hide Files matching *.
On Windows you still have to list every file in order to find every directory so there's no speed increase to be gained while listing directories, but you will get the increase associated with not drawing/sorting each file item and not getting extra information like file icons and the Description column.
Thanks Leo, is there away to do this with one click on a button or menu?
Isn't this what "Mixed (No Folders)" does?
This seems to work:
Set HIDEFILTERFILENAME=*
Set FLATVIEW=On,Mixed
No files, not no folders. 
It does no folders only files. I believe he is talking about the exact opposite--no files only folders.
Oops should have read more carefully
Set HIDEFILTERFILENAME=*
Set FLATVIEW=On,Mixed
This works if you select the menu item twice (strange), but thanks Leo
it does what I want it to do although the sub folders don't step to the
right like Mixed Mode normaly does.
"Flies spread disease, keep yours closed!"[/quote]
FlatView - Mixed does not step subfolders to the right, but FlatView - Grouped does.
So instead of this:
Set HIDEFILTERFILENAME=*
Set FLATVIEW=On,Mixed
Use this:
Set HIDEFILTERFILENAME=*
Set FLATVIEW=on,Grouped
When I click once on this button, the file display is changed to FlatView - Grouped (which indents your sub folders like you want), and all files are hidden. When I click a second time on this button, the file display remains in FlatView - Grouped, but the files are displayed again.
The Set HIDEFILTERFILENAME acts like a toggle, turning the filter on and off. If you just had that command in a button by itself, you see that Opus highlights it like a toggle whenever that filter is in effect.
If you have to click twice, it may have something to do with any filter you had previously set.
If you want to toggle between Details ungrouped and FlatView Grouped (No Files), use this button
Set HIDEFILTERFILENAME=*
Set FLATVIEW=Toggle,Grouped
That isn't a bad little button.
Oops! Copied-and-pasted but forgot to make the change. I have fixed my earlier post.
I tried this new button and got the same results, I have to click the
button twice to see only folders but sub folders do step right. I have a hide files filter "*.(dat|db|ini)" as a default for all folders so I removed it and the button still needs to be clicked twice to only show folders.
Also while trying to find a solution I found an undocumented switch for
the Set command "Clearfilters". What does this switch do?
You could set up an Opus 3 button button where a left click runs this command line:
Set FLATVIEW=Grouped HIDEFILTERFILENAME=*
And a right click runs this line:
Set FLATVIEW=Off CLEARFILTERS
The second button should also answer your other question about CLEARFILTERS as it's used to clear the filters set by the first button.
Just in case someone is subscribed to this topic, or finds it in the future via searching, here's a link to what may be a preferably solution using Lister Styles:
Edit 2019: If you want a button that toggles Flat View and the filter at once:
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