I'm new to directory Opus 8 so I probably gonna ask some stupid questions. 
Adding directories/programs to the toolbar:
I have 5 directories that I use 70% of my computing time.
I would like to put them as a button/icon on the toolbar.
Just like the applications toolbar.
(I know there is a favourites dropdown menu)
Filter:
I want to filter so that only *.pdf files are visible. How do I do that?
Hi there nerd... don't fear to ask questions dude!
If you click RMB (right mouse button) on any toolbar and select the Customize context menu option... this puts you into 'Customize mode' 
. Once there, you can minmize the Customize dialog and still navigate through folders... and as you find the ones you're interested in, drag and drop the folders to whatever toolbar you want. This automatically creates a button for each folder you drop onto the toolbar. Each button runs the command Go "drive:\path\to\folder" where the drive and path info is obviously specific to whatever folder you've selected...
Also, while still in customize mode... try copying the exact text inside this 'code' box, then click RMB somewhere on a toolbar and select the Paste option from the context menu.
<?xml version="1.0"?>
<button display="label" effect="gray" field_type="filter" size="297">
<guid>{A1E7C6C1-6D49-446F-A357-91E9ECE42891}</guid>
<label>Filter</label>
<tip>Directly enter a wildcard pattern to filter files visible in the current Lister</tip>
<template>realtime</template>
<icon1>0</icon1>
<function type="normal">
<instruction>Set FILTER</instruction>
</function>
</button>
This will create a dynamic file and folder 'filter' field on your toolbar which will let you type whatever you want into it to 'show' only files which match the pattern you've typed.
Otherwise, you might like to go with something like:
<?xml version="1.0"?>
<button display="both" effect="gray" icon_size="large">
<guid>{277804AA-9D6C-44C3-A82F-475FE761903D}</guid>
<label>Show PDF files only</label>
<tip>Show PDF files only</tip>
<icon1>43</icon1>
<function type="normal">
<instruction>Set SHOWFILTERFILENAME *.pdf</instruction>
</function>
</button>
This will create a button that you can click that will just filter/show PDF files automatically. Clicking the button again will return your view to normal...
You'll have to first 'Close' the Customize dialog to actually use any of these buttons/fields... and once you do clicking on any of the folder buttons you dragged to your toolbar will make Opus take you to those folders (that's what the internal 'Go' function does which the buttons run).
There are other ways to do all this, but the steps above show you two quick 'shortcuts' for creating buttons on a toolbar. Similar to dragging 'folders' to a toolbar while in Customize mode... dragging an application (executable) to a toolbar creates a 'shortuct' to that application. You can also drag a regular windows shortcut to the toolbar, but then that's an unnecessary 'shortcut' to a shortcut 
.
Reply back if you have any questions and welcome to Opus!
Edit note- you mentioned you were aware there was a 'Favorites' drop down menu. If you'd like to use that, shout back. The method above 'works', but if you use Opus 'favorites' you can drag a different command to the toolbar which will show you a list of your favorites and will be updated dynamically as you modify your favorites... which is cool too.
I asked for an explanation. And what I got? A five day Opus course 
Great reply mate!
No need to explain the other ways to do the same because this works great for me!
Thanks again!
Lets says I create 4 buttons each with their own Filter command on 4 file types (xls, doc, ppt, pdf).
Is there a way to make them work in unison? i.e., if I select the XLS and PPT icons, it will display both filter commands? As of right now, it will only display the most recently pushed ones so I can't display both file types.... only one at a time.
I'm not aware of a way to use a button to force Opus to add a new filter to an existing one in place. You could set a button up to show those 4 file types by using this command in a button:
Set SHOWFILTERFILENAME *.(xls|doc|ppt|pdf)
However in a situation like this I would use the "Show Files Field" command instead. That puts a box on the toolbar of your choice where you can type in any filter at any time. For example if I typed this into that box:
*.(xls|doc|ppt|pdf)
You would see only those 4 file types. If you want to add (or delete) another file type, just add (or delete) it to what you have in that Show Files Field box. The Show Files Field command box is also handy for giving you a visual indication of the filter currently in use.
In addition to John's idea - the Show Files Field provides a drop-down history, meaning that once you have typed in the various permutations you require they will be available quickly and easily.
Tanis man... you shopping for a new avatar ?
Not really. Bored with the one I was using though.
I'm running OPUS on the trial. Very impressive. The filtering box is great.
How do you change the generic folder icon to something more distinctive?
Because I'm running late and will have to fire myself if I don't get to my job on time (I'm self employed ya know lol) I'm just going to copy and paste what I have in my ever growing Opus text database of notes. The below should tell you how to change folder icons to something else (in my situation I wanted a camera folder icon) while the second section explains how to change folder colors. Bear in mind this is for Windows XP.
Hope you can figure it out, if not others will be glad to chip in here soon.
Off to work.
To set a bunch of folders to have a camera icon first create one folder icon the normal way. Which is:
I just click on the desired folder, select PROPERTIES, then tick the CUSTOMIZE tab and at the bottom of that click the CHANGE ICON button to select a new folder icon. That creates or modifies a hidden file in that folder named Desktop.ini which contains the icon info.
Then drag and drop the desktop.ini file in that folder to all the other folders you also want to have the camera icon.
The last step is to use the DOpus SetAttr command to set each of those folder attributes to READ ONLY. Refresh the display and all should have camera icons.
Folder Colors:
(From Jon in the icons section of the Resource Forum)
To assign one of the icons to a folder in Windows XP:
Notes:
A little follow up to what I posted earlier. My method to change folder icons should work but it's overkill. It's been quite awhile since a bunch of us hammered out a method to change folder icons and at the time we did so it seemed necessary to do it the way I mentioned last time. Now with the current version of XP you can forget about having to change the folder attributes to read only. Just select the folder and go to properties to customize it.
I gotta update some of my notes! lol
I'm self employed too. Fifteen years and my mom still wants to know when I'm getting a real job.
I apprecitate the help, you got me rolling. I've got the icon nested with three folders so different clicks on the mouse buttons takes me to a different folder. Cool.