public TaskDialogButton ShowModal()

in Common/Product/SharedProject/TaskDialog.cs [156:295]
125 lines of code
25 McCabe index (conditional complexity)

        public TaskDialogButton ShowModal() {
            var config = new NativeMethods.TASKDIALOGCONFIG();
            config.cbSize = (uint)Marshal.SizeOf(typeof(NativeMethods.TASKDIALOGCONFIG));
            config.pButtons = IntPtr.Zero;
            config.pRadioButtons = IntPtr.Zero;

            var uiShell = (IVsUIShell)_provider.GetService(typeof(SVsUIShell));
            if (uiShell == null) {
                // We are shutting down, so return the default
                return SelectedButton;
            }
            uiShell.GetDialogOwnerHwnd(out config.hwndParent);
            uiShell.EnableModeless(0);

            var customButtons = new List<TaskDialogButton>();
            config.dwCommonButtons = 0;

            foreach (var button in Buttons) {
                var flag = GetButtonFlag(button);
                if (flag != 0) {
                    config.dwCommonButtons |= flag;
                } else {
                    customButtons.Add(button);
                }
            }

            try {
                if (customButtons.Any()) {
                    config.cButtons = (uint)customButtons.Count;
                    var ptr = config.pButtons = Marshal.AllocHGlobal(customButtons.Count * Marshal.SizeOf(typeof(NativeMethods.TASKDIALOG_BUTTON)));
                    for (int i = 0; i < customButtons.Count; ++i) {
                        NativeMethods.TASKDIALOG_BUTTON data;
                        data.nButtonID = GetButtonId(null, null, i);
                        if (string.IsNullOrEmpty(customButtons[i].Subtext)) {
                            data.pszButtonText = customButtons[i].Text;
                        } else {
                            data.pszButtonText = string.Format("{0}\n{1}", customButtons[i].Text, customButtons[i].Subtext);
                        }
                        Marshal.StructureToPtr(data, ptr + i * Marshal.SizeOf(typeof(NativeMethods.TASKDIALOG_BUTTON)), false);
                    }
                } else {
                    config.cButtons = 0;
                    config.pButtons = IntPtr.Zero;
                }

                if (_buttons.Any() && SelectedButton != null) {
                    config.nDefaultButton = GetButtonId(SelectedButton, customButtons);
                } else {
                    config.nDefaultButton = 0;
                }

                if (_radioButtons.Any()) {
                    config.cRadioButtons = (uint)_radioButtons.Count;
                    var ptr = config.pRadioButtons = Marshal.AllocHGlobal(_radioButtons.Count * Marshal.SizeOf(typeof(NativeMethods.TASKDIALOG_BUTTON)));
                    for (int i = 0; i < _radioButtons.Count; ++i) {
                        NativeMethods.TASKDIALOG_BUTTON data;
                        data.nButtonID = GetRadioId(null, null, i);
                        data.pszButtonText = _radioButtons[i].Text;
                        Marshal.StructureToPtr(data, ptr + i * Marshal.SizeOf(typeof(NativeMethods.TASKDIALOG_BUTTON)), false);
                    }

                    if (SelectedRadioButton != null) {
                        config.nDefaultRadioButton = GetRadioId(SelectedRadioButton, _radioButtons);
                    } else {
                        config.nDefaultRadioButton = 0;
                    }
                }

                config.pszWindowTitle = Title;
                config.pszMainInstruction = MainInstruction;
                config.pszContent = Content;
                config.pszExpandedInformation = ExpandedInformation;
                config.pszExpandedControlText = ExpandedControlText;
                config.pszCollapsedControlText = CollapsedControlText;
                config.pszFooter = Footer;
                config.pszVerificationText = VerificationText;
                config.pfCallback = Callback;
                config.hMainIcon = (IntPtr)GetIconResource(MainIcon);
                config.hFooterIcon = (IntPtr)GetIconResource(FooterIcon);

                if (Width.HasValue) {
                    config.cxWidth = (uint)Width.Value;
                } else {
                    config.dwFlags |= NativeMethods.TASKDIALOG_FLAGS.TDF_SIZE_TO_CONTENT;
                }
                if (EnableHyperlinks) {
                    config.dwFlags |= NativeMethods.TASKDIALOG_FLAGS.TDF_ENABLE_HYPERLINKS;
                }
                if (AllowCancellation) {
                    config.dwFlags |= NativeMethods.TASKDIALOG_FLAGS.TDF_ALLOW_DIALOG_CANCELLATION;
                }
                if (UseCommandLinks && config.cButtons > 0) {
                    config.dwFlags |= NativeMethods.TASKDIALOG_FLAGS.TDF_USE_COMMAND_LINKS;
                }
                if (!ShowExpandedInformationInContent) {
                    config.dwFlags |= NativeMethods.TASKDIALOG_FLAGS.TDF_EXPAND_FOOTER_AREA;
                }
                if (ExpandedByDefault) {
                    config.dwFlags |= NativeMethods.TASKDIALOG_FLAGS.TDF_EXPANDED_BY_DEFAULT;
                }
                if (SelectedVerified) {
                    config.dwFlags |= NativeMethods.TASKDIALOG_FLAGS.TDF_VERIFICATION_FLAG_CHECKED;
                }
                if (CanMinimize) {
                    config.dwFlags |= NativeMethods.TASKDIALOG_FLAGS.TDF_CAN_BE_MINIMIZED;
                }

                config.dwFlags |= NativeMethods.TASKDIALOG_FLAGS.TDF_POSITION_RELATIVE_TO_WINDOW;

                int selectedButton, selectedRadioButton;
                bool verified;
                ErrorHandler.ThrowOnFailure(NativeMethods.TaskDialogIndirect(
                    ref config,
                    out selectedButton,
                    out selectedRadioButton,
                    out verified
                ));

                SelectedButton = GetButton(selectedButton, customButtons);
                SelectedRadioButton = GetRadio(selectedRadioButton, _radioButtons);
                SelectedVerified = verified;
            } finally {
                uiShell.EnableModeless(1);

                if (config.pButtons != IntPtr.Zero) {
                    for (int i = 0; i < customButtons.Count; ++i) {
                        Marshal.DestroyStructure(config.pButtons + i * Marshal.SizeOf(typeof(NativeMethods.TASKDIALOG_BUTTON)), typeof(NativeMethods.TASKDIALOG_BUTTON));
                    }
                    Marshal.FreeHGlobal(config.pButtons);
                }
                if (config.pRadioButtons != IntPtr.Zero) {
                    for (int i = 0; i < _radioButtons.Count; ++i) {
                        Marshal.DestroyStructure(config.pRadioButtons + i * Marshal.SizeOf(typeof(NativeMethods.TASKDIALOG_BUTTON)), typeof(NativeMethods.TASKDIALOG_BUTTON));
                    }
                    Marshal.FreeHGlobal(config.pRadioButtons);
                }
            }

            return SelectedButton;
        }