Bad file dialog on W32 popped up by a click on C source

[Eli Zaretskii <eliz@gnu.org>]

"C-h f some-function RET" shows "C source file" for functions defined
in C.  If you click on the xref, and if the source files are not in
the place where Emacs expects to find them (e.g., if you removed the
source tree), Emacs pops up a file dialog asking you to find the
directory of the source file.  So far so good, but, at least on W32, I
see 2 problems with this dialog:

  . it doesn't say what directory it is looking for and doesn't show
    me the name of the file, so I need to guess that it wants the src
    directory

  . if I select the src directory where the file lives and click Open,
    it errors out saying "Current Directory -- file not found"

The latter problem seems to be specific to MS-Windows, as it overrides
the file name with a literal string "Current Directory"; this works
with File->Open Directory from the menu bar, but fails in the above
situation.  I'm not sure whether the former problem is MS-Windows
specific.

Any suggestions for how to solve this?