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Trapping for Ctrl-F4

Posted on 1998-09-07
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Last Modified: 2010-04-06
Hi

I have a MDI applicatin with several child forms. How do I prevent the user from pressing Ctrl-F4 to close the child for (similarly Ctrl-F6 to switch between forms)?

Regards
Keith
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Question by:keithcsl
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6 Comments
 
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Accepted Solution

by:
viktornet earned 50 total points
ID: 1338903
procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
  if (Shift = [ssCtrl])and (key = VK_F4) then
    ShowMessage('Ctrl + F4 was just pressed');
   //Instead of the message do you stuff here
end;
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Author Comment

by:keithcsl
ID: 1338904
victornet

Hi, have you tried your code and got it going? I wrote the exact same code but have failed to trap it. I might be doing it wrong:

In the OnCloseQuery event:
  if flgCannotClose = True then
    CanClose := False;

In the KeyDown event of the form
  if (Shift = [ssctrl]) AND (key = VK_F4) then
    flgCannotClose = True;

Regards
Keith
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Author Comment

by:keithcsl
ID: 1338905
Victornet

I have noticed that the OnCloseQuery is called before the OnKeyDown, that's why I can't trap the Ctrl-F4

It works for Ctrl-F3, etc

Regards
Keith
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Expert Comment

by:viktornet
ID: 1338906
Hello Keith =)

Here is what you do......
-----------
var
  flgCannotClose : boolean = False;
procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
  flgCannotClose := True = (Shift = [ssctrl]) AND (key = VK_F4);
end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
   if flgCannotClose = True then
     Action := caNone;
end;

procedure TForm1.FormKeyUp(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
  flgCannotClose := False;
end;
----------
Regards,
Viktor Ivanov
0
 
LVL 1

Author Comment

by:keithcsl
ID: 1338907
Oh boy, I think it must have been the late nights that have made me a little blind.

Viktornet, thanks to your code above, I have just realised that to avoid the forms from closing, all I have to do is to set
  Action := caNone
in the OnClose event of the form

Thanks a lot

Regards
Keith
0
 
LVL 10

Expert Comment

by:viktornet
ID: 1338908
No prob :-)

Regards,
Viktor Ivanov
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