Assigning a Procedure not working

[RedOctober]

Platform:  Lazarus 1.8.1, FPC 3.0.5

I'm using a radio group component to both display info and to allow the user to select a choice.  This means that the OnSelectionchange needs to be shut off while I set it to the current value, then, turn it on again for the user to make a selection.  I'm trying to do this by setting the .OnSelectionChanged event to nil in the FormCreate procedure, and then in the FormShow procedure, reassign it.  Like this:

Code: Pascal  [Select][+][-]

1. procedure TForm2.RadioGroup1SelectionChanged(Sender: TObject);
2. begin
3.   ShowMessage('My Selection has Changed');
4. end;
5.  
6. procedure TForm2.FormCreate(Sender: TObject);
7. begin
8.   RadioGroup1.OnSelectionChanged := nil;
9. end;
10.  
11. procedure TForm2.FormShow(Sender: TObject);
12. begin
13.   RadioGroup1.OnSelectionChanged := RadioGroup1SelectionChanged;
14. end;  
15.  

The line RadioGroup1.OnSelectionChanged := RadioGroup1SelectionChanged; in the FormShow will not compile. The error message is:

Compile Project, Target: unable_to_assign_prc.exe: Exit code 1, Errors: 2
unit2.pas(47,37) Error: Wrong number of parameters specified for call to "RadioGroup1SelectionChanged"
unit2.pas(35,18) Error: Found declaration: RadioGroup1SelectionChanged(TObject);

What am I doing wrong.  I'm tired and must be missing the obvious.  Thanks in advance for your help.

I have attached a demo project (missed it on my first post)

[Blaazen]

Code: Pascal  [Select][+][-]

1.   RadioGroup1.OnSelectionChanged := @RadioGroup1SelectionChanged;
2.  

[jamie]

I consider that a bug!

I just checked my old Delphi and it's there too.

Normally when ever you set controls that do as what a USER does, the software set should not
trigger the OnClick event.. Only the user with their mouse should be doing that.

 Maybe we can get that fixed with a property option ..

 In any case,

 In the OnClick Event you can do this..

Code: Pascal  [Select][+][-]

1. If Visible Then  // This is checking the FORM for visibility.
2.  begin
3.   //Do your onclick code here.
4.  End;
5.  

You also could do this..

In your Onclick event test for the TAG of the control..

If TAG = 1 then you can allow the contents of that event to take place..

when ever you want to move the INDEX of that control without code execution.... do this..

RadoGroup.Tag := O;

Radgroup.ItemIndex := ?

Tag := 1;
etc//

In the event;
If RadioGroup1.Tag = 1 then
Begin
.....
end;

[RedOctober]

Thanks.  Blaazen's fix worked.  I forgot about "pointer to address"  "@" symbol.