As for problem with "do"s and "don"s, can you please bit a little more specific. Can you please post names of the files in your project - this will allow me to reproduce the problem and fix it. What was the search pattern you used and what is the result you expected to see. Also, what version of SlickEdit you have?
It's such a basic problem that you couldn't miss it, so maybe it only happens on SE 13, or maybe it is somehow being affected by some other macro. I'll try to describe it more thoroughly:
SlickEdit 13.0.0 r17, on Vista.
Suppose the project has 3 files:
A.c
Ab.c
D.c
Steps:
1. Press the key bound to -open-project-file.
Result: the dialog opens and lists all files: A.c, Ab.c, D.c.
2. Type a letter that you expect will filter the list: in this example, try "a".
Result: the letter appears in the text box at the top, but the list is not filtered at all yet, it still lists all files: A.c, Ab.c, D.c (it should list only files that match "a", so it should only list A.c, Ab.c).
3. Type a second letter that you expect to further filter the list: in this example, try "b".
Result: now the list gets filtered per the letter you typed in step 2 (but not step 3): it lists A.c, Ab.c (it should list only files that match "ab", so it should only list Ab.c).
4. Press the Backspace key.
Result: now the list is filtered by both the characters from steps 2 and 3: it lists only Ab.c (it should list files that match "a", so it should list A.c, Ab.c).