protected override bool RunDialog(IntPtr hwndOwner) { InteropUtil.Assume(Marshal.SystemDefaultCharSize == 2, "The character size should be 2"); IntPtr nativeBuffer = Marshal.AllocCoTaskMem(InteropUtil.NumberOfFileChars * 2); IntPtr filterBuffer = IntPtr.Zero; _selected = new List <string>(); try { var openFileName = new InteropUtil.OpenFileName(); openFileName.Initialize(); openFileName.hwndOwner = hwndOwner; var chars = new char[InteropUtil.NumberOfFileChars]; try { if (File.Exists(Path)) { if (AcceptFiles) { string fileName = System.IO.Path.GetFileName(Path); int length = Math.Min(fileName.Length, InteropUtil.NumberOfFileChars); fileName.CopyTo(0, chars, 0, length); openFileName.lpstrInitialDir = System.IO.Path.GetDirectoryName(Path); } else { openFileName.lpstrInitialDir = System.IO.Path.GetDirectoryName(Path); } } else if (Directory.Exists(Path)) { openFileName.lpstrInitialDir = Path; } else { //the path does not exist. //We don't just want to throw it away, however. //The initial path we get is most likely provided by the user in some way. //It could be what they typed into a text box before clicking a browse button, //or it could be a value they had entered previously that used to be valid, but now no longer exists. //In any case, we don't want to throw out the user's text. So, we find the first parent //directory of Path that exists on disk. //We will set the initial directory to that path, and then set the initial file to //the rest of the path. The user will get an error if the click "OK"m saying that the selected path //doesn't exist, but that's ok. If we didn't do this, and showed the path, if they clicked //OK without making changes we would actually change the selected path, which would be bad. //This way, if the users want's to change the folder, he actually has to change something. string pathToShow; InitializePathDNE(Path, out openFileName.lpstrInitialDir, out pathToShow); pathToShow = pathToShow ?? String.Empty; int length = Math.Min(pathToShow.Length, InteropUtil.NumberOfFileChars); pathToShow.CopyTo(0, chars, 0, length); } } catch { } Marshal.Copy(chars, 0, nativeBuffer, chars.Length); openFileName.lpstrFile = nativeBuffer; if (!AcceptFiles) { string str = string.Format("Folders\0*.{0}-{1}\0\0", Guid.NewGuid().ToString("N"), Guid.NewGuid().ToString("N")); filterBuffer = openFileName.lpstrFilter = Marshal.StringToCoTaskMemUni(str); } else { openFileName.lpstrFilter = IntPtr.Zero; } openFileName.nMaxCustFilter = 0; openFileName.nFilterIndex = 0; openFileName.nMaxFile = InteropUtil.NumberOfFileChars; openFileName.nMaxFileTitle = 0; openFileName.lpstrTitle = Title; openFileName.lpfnHook = m_hookDelegate; openFileName.templateID = InteropUtil.IDD_CustomOpenDialog; openFileName.hInstance = Marshal.GetHINSTANCE(typeof(SelectFileAndFolderDialog).Module); openFileName.Flags = InteropUtil.OFN_DONTADDTORECENT | InteropUtil.OFN_ENABLEHOOK | InteropUtil.OFN_ENABLESIZING | InteropUtil.OFN_NOTESTFILECREATE | InteropUtil.OFN_ALLOWMULTISELECT | InteropUtil.OFN_EXPLORER | InteropUtil.OFN_FILEMUSTEXIST | InteropUtil.OFN_PATHMUSTEXIST | InteropUtil.OFN_NODEREFERENCELINKS | InteropUtil.OFN_ENABLETEMPLATE | (ShowReadOnly ? 0 : InteropUtil.OFN_HIDEREADONLY); m_useCurrentDir = false; bool hideFileExtSettingChanged = false; try { if (GetHideFileExtensionSetting()) { HideFileExtension(false); hideFileExtSettingChanged = true; } bool ret = false; try { ret = InteropUtil.GetOpenFileNameW(ref openFileName); } catch (Exception e) { IntPtr hParent = InteropUtil.AssumeNonZero(InteropUtil.GetParent(m_hWnd)); InteropUtil.SendMessage(hParent, InteropUtil.WM_CLOSE, 0, 0); throw e; } //var extErrpr = InteropUtil.CommDlgExtendedError(); //InteropUtil.CheckForWin32Error(); if (m_useCurrentDir) { Path = m_currentFolder; return(true); } else if (ret) { Marshal.Copy(nativeBuffer, chars, 0, chars.Length); int firstZeroTerm = ((IList)chars).IndexOf('\0'); if (firstZeroTerm >= 0 && firstZeroTerm <= chars.Length - 1) { Path = new string(chars, 0, firstZeroTerm); } } return(ret); } finally { //revert registry setting if (hideFileExtSettingChanged) { HideFileExtension(true); } } } finally { Marshal.FreeCoTaskMem(nativeBuffer); if (filterBuffer != IntPtr.Zero) { Marshal.FreeCoTaskMem(filterBuffer); } } }