Clicking on search in directory does not bring up the search dialog if there are no files open in the Editor. I don't think this function should depend on which files, if any, are open.
(I look on search in directory as equivalent to "find in files" in other applications.)
> Search dialog should not depend on which files are open.
Actually, the search dialog attempts to guess the search expression. So it depends on the current word from the current file.
Under which circumstances can we have, no one file opened? (and want to search :)
> Search in directory is equivalent to "find in files".
May be yes or may be no. Dev-PHP implements two searches: in project files, and in opened files. Both don't mean search in (any) files. The scope is fixed, we can't change the root directory on the fly. I think that other applications can do that, but it has no meaning here?