TaskDialog: implement OnNavigated (native Windows Vista+ only) and OnHelp.

While Delphi has DoOnHelp protected method, it seems they do not have OnHelp (GOKY).

lcl/dialogs.pp

@@ -642,7 +642,9 @@ type
     FOnDialogCreated: TNotifyEvent;
     FOnDialogDestroyed: TNotifyEvent;
     FOnExpanded: TNotifyEvent;
+    FOnHelp: TNotifyEvent;
     FOnHyperlinkClicked: TNotifyEvent;
+    FOnNavigated: TNotifyEvent;
     FOnRadioButtonClicked: TNotifyEvent;
     FOnTimer: TTaskDlgTimerEvent;
     FOnVerificationClicked: TNotifyEvent;
@@ -674,9 +676,12 @@ type
     procedure DoOnExpandButtonClicked(Expanded: Boolean); dynamic;
     procedure DoOnTimer(TickCount: Cardinal; var Reset: Boolean); dynamic;
     procedure DoOnVerificationClicked(Checked: Boolean); dynamic;
-    //procedure DoOnHelp; dynamic;
+    procedure DoOnHelp; dynamic;
     procedure DoOnHyperlinkClicked(const AURL: string); dynamic;
-    //procedure DoOnNavigated; dynamic;
+
+    //requires that a TaskDialog has pages, (see: https://learn.microsoft.com/en-us/dotnet/api/system.windows.forms.taskdialogpage.navigate?view=windowsdesktop-7.0)
+    //which might be implemented in a derived class, but the event handler must be in base class for Delphi compatibility.
+    procedure DoOnNavigated; dynamic;
 
     procedure SetRadioButtonFromRadioIndex(AIndex: Integer);
   public
@@ -720,6 +725,8 @@ type
     property OnTimer: TTaskDlgTimerEvent read FOnTimer write FOnTimer;
     property OnRadioButtonClicked: TNotifyEvent read FOnRadioButtonClicked write FOnRadioButtonClicked;
     property OnHyperlinkClicked: TNotifyEvent read FOnHyperlinkClicked write FOnHyperlinkClicked;
+    property OnNavigated: TNotifyEvent read FOnNavigated write FOnNavigated;
+    property OnHelp: TNotifyEvent read FOnHelp write FOnHelp;
   end;
 
   TTaskDialog = class(TCustomTaskDialog)

lcl/include/taskdialog.inc

@@ -220,6 +220,12 @@ begin
     FOnVerificationClicked(Self);
 end;
 
+procedure TCustomTaskDialog.DoOnHelp;
+begin
+  if Assigned(FonHelp) then
+    FOnHelp(Self);
+end;
+
 procedure TCustomTaskDialog.DoOnHyperlinkClicked(const AURL: string);
 begin
   FURL := AURL;
@@ -227,6 +233,12 @@ begin
     FOnHyperlinkClicked(Self);
 end;
 
+procedure TCustomTaskDialog.DoOnNavigated;
+begin
+  if Assigned(FOnNavigated) then
+    FOnNavigated(Self);
+end;
+
 procedure TCustomTaskDialog.SetRadioButtonFromRadioIndex(AIndex: Integer);
 begin
   if (AIndex >= TaskDialogFirstRadioButtonIndex) and (AIndex-TaskDialogFirstRadioButtonIndex < RadioButtons.Count) then

lcl/interfaces/win32/win32wsdialogs.pp

@@ -1721,7 +1721,11 @@ begin
       lParam: Must be zero.
       Return value: The return value is ignored.
       }
-      if IsConsole then writeln('ToDo: implement OnNavigated');
+      Assert((Dlg is TCustomTaskDialog),'TaskDialogCallbackProc: dwRefData is NOT a TCustomTaskDialog');
+      {$PUSH}
+      {$ObjectChecks OFF}
+      TTaskDialogAccess(Dlg).DoOnNavigated;
+      {$POP}
     end;
     TDN_TIMER:
     begin
@@ -1769,7 +1773,11 @@ begin
     end;
     TDN_HELP:
     begin
-      if IsConsole then writeln('ToDo: implement TDN_HELP??');
+      Assert((Dlg is TCustomTaskDialog),'TaskDialogCallbackProc: dwRefData is NOT a TCustomTaskDialog');
+      {$PUSH}
+      {$ObjectChecks OFF}
+      TTaskDialogAccess(Dlg).DoOnHelp;
+      {$POP}
     end;
   end;
 end;

lcl/taskdlgemulation.pp

@@ -67,6 +67,7 @@ type
     procedure OnRadioButtonClick(Sender: TObject);
     procedure OnVerifyClicked(Sender: TObject);
     procedure OnTimer(Sender: TObject);
+    procedure DoOnHelp;
 
   protected
     procedure SetupControls;
@@ -700,6 +701,14 @@ begin
     ResetTimer;
 end;
 
+procedure TLCLTaskDialog.DoOnHelp;
+begin
+  {$PUSH}
+  {$ObjectChecks OFF}
+  {%H-}TTaskDialogAccess(FDlg).DoOnHelp;
+  {$POP}
+end;
+
 procedure TLCLTaskDialog.OnRadioButtonClick(Sender: TObject);
 var
   ButtonID: Integer;
@@ -957,7 +966,11 @@ begin
     if (Key = VK_F4) and (ssAlt in Shift) then//IMPORTANT: native task dialog blocks Alt+F4 to close the dialog -> we have to block it as well
       Key := 0;
   end;
-
+  if (Key = VK_F1) and (Shift = []) then
+  begin
+    Key := 0;
+    DoOnHelp;
+  end;
   inherited KeyDown(Key, Shift);
 end;