Using FindVCLWindow to call WinHelp32 (WinXP Pro SP3 32bit) in Delphi

Question

what is wrong there?

procedure TForm1.VCLHelpClick(Sender: TObject);
var Ctrl : TWinControl;
 begin
 Ctrl := FindVCLWindow(Mouse.CursorPos);
 if Ctrl <>         


        

Answer 1

Working code:

procedure TForm1.VCLHelpClick(Sender: TObject);
var WCtrl : TWinControl;
begin
  WCtrl := FindVCLWindow(Mouse.CursorPos);
  if WCtrl <> nil then
   Application.HelpCommand(HELP_CONTEXT, wCtrl.HelpContext);
end;

P.S. all previous code probobly was ok too, but i rechecked my event handlers and found that in one tlabel it was missing ( althought when I clicked to the ones that had onclick, it did not work). Plus ... problem probobly was the faulty cursor check.

Ok, thanks for support, guys!

Answer 2

Have you tried debugging the code? And can you tell us what part went wrong.

Besides, why don't you use the helpcontext like:

procedure TForm1.VCLHelpClick(Sender: TObject);
var Ctrl : TWinControl;
begin
  if Form2.Cursor <> crHelp then   // Are you sure this is Form2???
    Exit;
  Ctrl := FindVCLWindow(Mouse.CursorPos);
  if Ctrl = nil then Exit;

  Application.HelpCommand(HELP_CONTEXT, Ctrl.HelpoContext);
end;

Looks like FindVCLControl does some other things. But the following code works:

procedure TForm1.Button1Click(Sender: TObject);
var
  ctrl : TControl;
  point : TPoint;
begin
  point := Mouse.CursorPos; // Mouse pos at screen
  Dec(point.X, Left); // Adjust for window.
  Dec(point.Y, Top);
  Dec(point.Y, GetSystemMetrics(SM_CYCAPTION)); // Adjust to client area.

  ctrl := ControlAtPos(point, True, True, True);

  // Do something with the control
end;

You probably need some more tweaking, but this works to get the control of a window from the position.