...By removing unneeded items from the file navigation window, you are reducing the number of choices the user must pick from and also preventing him from opening the wrong kinds of files...
...Good feedback just means making sure that the user knows what your program is doing at any given time, especially if the program is busy doing something which makes him wait...
...An even better solution would be to select a good default choice for the user and give him the option to change it...
... In short, a user will learn only what he must in order to do his job...
Ctrl-F "her", "she": 0 matches
Another tip to design good software: don't assume all your users are male :)
This is an okay stab at a HIG, although it is severely lacking in examples and screenshots, for a document that deals with graphical user interfaces.
Good past attempts that are worth the read if you're into this kind of stuff include the original Macintosh HIG, as well as NextStep User Interface Guidelines. I also quite liked the Hypercard Stack Design Guidelines. Gnome once had an okay-ish HIG (which I contributed to), not sure how well up to date it's been kept through the years. KDE, despite being better on the eye candy front compared to Gnome, was always lacking behind in terms of actual concrete guidelines for developers.