Is it possible to user folders other than ClientTerminal_folder \experts?

are you talking about MQL4 SOURCE files?

if so:

source code files and their .ex4 compiler o/p must be in documented dirs of the experts tree.

eg:

indicators in ...\experts\indicators

experts in ...\experts

scripts in ...\experts\scripts

include files of type <file.mqh> live in ...\experts\include, however they can live in same dir as source code containing #include directive if "file.mqh" syntax used.

.

are you talking about files that are used and/or created in your program?

if so:

the FileOpen() docs state:

"Files can only be opened in the terminal_directory\experts\files folder (terminal_directory\tester\files if for expert testing) or in its subfolders."

(btw:I have found that any legal[as in above line] dir path you specify will be used and if dirs not present, FileOpen() will create them)

.

are you wanting to work on files located elsewhere?

you must use non-ClientTerminal file handling, eg: Windows API = You can find much on this forum including working examples/functions etc.

using Windows API is talked about and demonstrated all over this site - there is not much cannot do given Terminal i/f hooks to masses of .dll's, yes?

Just use the search box top right.