I'm new to Opus, i'm trying to make a hotkey that makes the selected files hidden.
(to hide folder.jpg ... if you can think of an even more useful method, feel free to mention!)
I got as far as setting up a new hotkey, but i'm stuck as to which setting to use...
Any help appreciated 
You can make a hotkey to hide selected files using the select command, I think, but if you just want folder.jpg to be hidden you can have that done automatically via Folder Formats (see the FAQ for details) on the Filters tab.
It does sound like you're looking to always hide a particular file - so go with Nudel's suggestion on configuring folder formats.
But - if you want to be able to hide selected files in the future 'temporarily' the full command would be:
Select NOPATTERN HIDESEL
hm, the filter idea seems to work pretty well, but it's not really what i had in mind.
I don't really want the all files called folder.jpg to automatically disappear, because i have that button to download album covers, and then it makes the folder.jpg ... but it doesn't always get the right one, so really i need to look at it, then hide it.
what i was thinking was the windows "hidden files" attribute... but i can't actually find a setting to hide/display those anyway. so i guess it wouldn't help.
and that code just makes the file disappear.. until you leave the folder... i'm not being mean, but i can't think of a use for that ! haha.
I use the following command in a menu item to toggle the showing/hiding of folder.jpg files.
Set HIDEFILTERFILENAME=folder.jpg
Works fine for me. It works as a toggle so you can easily switch between showing and hiding the file.
Just go to the Folder Format, Filters tab and click the H attribute under "Hide Filter".
Your probably best off combining both Tanis and Nudel's suggestions...
Modify your folder format to always hide 'folder.jpg' files, so that when your listers load, the file is already hidden. When you want to specifically look at the file - run Tanis code from a button/hotkey etc to easily see the file then click it again when done to not see it.
You could do it with the 'hidden' attribute as well, and change the command to Set HIDEFILTERATTR=h but then you'll always have to manually set the files as hidden in the first place - which is one extra step to the same result.
PHPBB_IMPORT_WARNING CODE_NEAR_LI
Requirements
If I understand your requirements correctly, you want to:
[ol][li] Set the Hidden File attribute on these files so they will not show in Windows Explorer, or Directory Opus[/li]
[li] Ensure Directory Opus hides files with the Hidden attribute.[/li][/ol]
Setting the Hidden File Attribute:
[quote="The authors of the Directory Opus Help file"]
The SetAttr command lets you modify the attributes, timestamps and descriptions of all selected files and folders. The attributes you can modify are Read Only (file can not be deleted or modified), Archive (file is marked for backup), Hidden (file is not normally displayed) and System (file is a system file). You can also set the creation and last modified time to a specific date and time. The default behavior of this command if no options are specified is to display the Set Attributes dialog. However, you can automate the procedure by specifying options to define which attributes and timestamps to modify. The command template for this function is:
ATTR/K, CLEARATTR/K, CREATED/K, DESCRIPTION/O, FILTER/K, MODIFIED/K, RECURSE/S, SETATTR/K, TOGGLEATTR/K
[ul][li] ATTR/K: This option lets you specify absolute attributes to change selected files to. The value string can consist of the letters r (read only), a (archived), h (hidden), s (system) or n (normal). For example, SetAttr ATTR=hs would set all selected file attributes to hidden and system.
[/li]
[li] SETATTR/K: This option lets you specify attributes to turn on in selected files. This has the effect of ‘adding’ attributes to those already set. It will not turn any existing attributes off.[/li][/ul][/quote]
A button with this Raw command below will invoke the Change Attributes & Times - Directory Opus dialog, in which you can set any and all file attributes, including the date/time stamps. Take some time to learn this dialog: the Set fields [b]add[/b] attributes, the Clear fields [b]remove[/b] attributes, you must use both Set and Clear, to end up with a desired resultant combination of file attributes.
SetAttrA button with this Raw command below will add the Hidden attribute to all selected files—any previously set file attributes are still retained.SetAttr SETATTR=H
A button with this Raw command below will set the Hidden attribute to all selected files—any previously set file attributes are removed.SetAttr ATTR=H
Hide Files with the Hidden Attribute Set:
To systematically hide files with the Hidden attribute from Directory Opus file listings, you need to configure the Hide options on the Filters tab of at least one of the following:[ol][li] The current lister folder format, accessible by using a toolbar button with this raw command:
Properties FOLDEROPTIONS[li] The defined Folder Format for that individual folder[/li]
[li] The Content Type Formats for the types of files that you are viewing[/li]
[li] The specific Default Format for drive type or the special type of folder handled by Directory Opus (i.e. zip files, collections, etc).[/li]
[li] The Custom Folder Format. This will be used if no Folder Options or Formats are not defined elsewhere.
NOTE: All of the above listed Folder Formats are accessible through Settings Menu > Preferences > Folders > Folder, with the exception of Folder Options for the currently open Lister. The Folder Options for the currently open Lister are an amalgamate of all the other formats. yet they can be edited for the currently open lister. However, once the Lister is closed, these Folder Options are discarded. By contrast, the other Folder Options are saved inside of a Folder Format, which DOpus will use in any Lister.
NOTE: The places to configure Folder Options are listed above in order of precedence. In general, the settings for each level trumps those listed below it. Thus, if you have defined a Folder Format for a given folder, its settings will override any Content Type Formats that may also apply to the contents of the same folder, or a Default Format that could have been applied to drive type on which the folder resides. However, in some cases settings can be allowed "pass through," allowing them to be pulled upward in the precedence order.[/li][/ol]I recommend that you configure Directory Opus Folder Options from the most general precedence level, to the more specific.