"open folder"ダイアログを表示し、選択されたパスを取得します
See Also: OpenFilePanel, SaveFolderPanel 関数

Open Folder Panel.
// Opens a directory dialog for copying all the png textures
// in the directory to where the current open scene resides
import System.IO;
@MenuItem("Examples/Load Textures to directory")
static function Apply () {
var path = EditorUtility.OpenFolderPanel("Load png Textures of Directory", "", "");
var files : String[] = Directory.GetFiles(path);
for(var file : String in files)
if(file.EndsWith(".png"))
File.Copy(file, EditorApplication.currentScene);
}