Author: Jonas Bilinkevicius

How can I wait until the form is actually painted on screen, before starting the 
processing so that I can be sure that any exceptions are displayed after the form 
is painted. I've considered a short timer in the OnCreate. Is there a better way 
(i.e. catching a Windows message)?

Answer:

Use an custom message:

1   const
2     UM_AFTERSHOW = WM_USER + 1001;
3   
4   type
5     TMyForm = class(TForm)
6       procedure FormShow(Sender: TObject);
7     private
8       procedure UMAfterShow(var Msg: TMessage); message UM_AFTERSHOW;
9     end;
10  
11  implementation
12  
13  procedure TMyForm.FormShow(Sender: TObject);
14  begin
15    PostMessage(Self.Handle, UM_AFTERSHOW, 0, 0);
16  end;
17  
18  procedure TMyForm.UMAfterShow(var Msg: TMessage);
19  begin
20    {your code here}
21  end;