I had completely misunderstood you, sorry. What you are talking about is a sort of mini explorer. If you use the scrollbar to the right of this so-called tool panel, you will hopefully see something like "my computer" at the top, all your disk drives, etc. It's just a more convenient way to access files if you want to work with several files in one folder. The drop-down list at the top you mentioned allows you to filter for a certain file type, say, html files, thus hiding all the others. Just drag your files from there to the main window to edit/read them. (But you can only edit existing files from there, no way to add new ones.)
Next to the mini explorer tab comes the ftp tab, here you can establish a connection to an ftp site and edit your files remotely. Basically it's used much like the explorer, except that the files are stored on a server (and you need an internet connection plus ftp account to see anything there). The blue box on the leftmost tab is a sort of project manager, see "Working With Projects" in the help file. Last but not least, there is the heart icon. On this tab, you can store links to files you edit on a regular basis, folders you have to access frequently, internet links, and external programs like e.g. a code beautifier, an external spell checker, a calculator, and whatnot. Hope that brings a little light into the dark. :) -- <http://forum.pspad.com/read.php?2,33947,33965> PSPad freeware editor http://www.pspad.com
