TEdit focus & caret

Question

I got two TEdit controls. When I tab out of edit1, edit2 receives the focus. On my OnExit event of Edit1 I have the following code:

procedure TForm1.Edit1Exit(Sender: TObject);
begin
  edit2.Enabled := false;
  edit2.Enabled := true;
  edit2.setfocus;
end;

Edit2 has the focus. However, there is no caret in it. I can start typing but it's confusing as I do not know which control has the focus.

I'm more interested on what's with the flipping of the Enabled property that's causing some messages to be not firing properly ? For instance edit2's OnEnter event is not being triggered.

This is on D2006 if it matters at all.

Thanks for the reply.

Answer 1

I don't understand why you disable and enable edit2, but you do this:

procedure TForm1.Edit1Exit(Sender: TObject);
begin
  edit2.Enabled := false;
  edit2.Enabled := true;
  edit2.setfocus;
  PostMessage(edit2.Handle, WM_SETFOCUS, 0, 0);
end;

BTW, I agree with Andreas Rejbrand.

Answer 2

I seriously suspect you are doing something in a bad way, and the best solution is most likely a redesign. You are not supposed to disable and then enable a control while it is receiving focus.

Answer 3

There's a bunch of codes between disabling and enabling edit2.

Having a lot of code in the OnExit event handler of the previous active control does not require to disable the next active control. That code will execute before the next active control shows up the caret and will be able to receive user input. Just make sure that it does nót pass execution over by something like starting a new thread or using Application.ProcessMessages.

Set Screen.Cursor to crHourGlass to make it clear for the user that the next active control is not ready yet.

Answer 4

Found an issue when OnActive for MainForm activates another form.

TMainForm.OnActivate;
begin
ChildForm.ShowModal;
end;

Control focus is set but does not work. The work around I found was sending PostMessage(Handle, WM_SETFOCUS, 0, 0); to the form handle.

procedure TChildForm.FocusControl(AWinControl: TWinControl);
begin
  try
    // http://stackoverflow.com/questions/7305296/tedit-focus-caret
    PostMessage(Handle, WM_SETFOCUS, 0, 0);
    PostMessage(AWinControl.Handle, WM_SETFOCUS, 0, 0); 
    if AWinControl.CanFocus then
       AWinControl.SetFocus;
  except
    on E: Exception do
    begin
      Error(Self, E);
    end;
  end;
end;