Pre-filter incompatible items in a file picker
I'm implementing a file picker to let users pick a simple textual file.
The prerequisite is the file must be writable.
However, a user might input the file's path by hand too.
Should I filter out the non-writable files in the dialog already?
The downside is that would result in a duplicated validation.
It would be better to show the files as disabled than to filter them out altogether; if they don't show at all, the user might wonder if it's an OS issue vs. something your system is doing deliberately. Disabled files communicate, "Our system can't use this file."