Author: Tomas Rutkauskas

I was wondering if there was any way to change the state of the TCheckBox control 
without setting off the OnClick Event Handler. If certain other properties are 
incorrect, I want void the state the event was set to by the Click, without setting 
of the event handler again.

Answer:

1   procedure TForm1.Button1Click(Sender: TObject);
2   begin
3     if Button1.Tag = 0 then
4     begin
5       SendMessage(CheckBox1.handle, BM_SETCHECK, BST_CHECKED, 0);
6       Button1.Tag := 1;
7     end
8     else
9     begin
10      SendMessage(CheckBox1.handle, BM_SETCHECK, BST_UNCHECKED, 0);
11      Button1.Tag := 0;
12    end;
13  end;
14  
15  procedure TForm1.CheckBox1Click(Sender: TObject);
16  begin
17    Showmessage('clicked');
18  end;