We help IT Professionals succeed at work.

Disable Closing application...

mories asked
Medium Priority
Last Modified: 2012-05-04
Hello people,

how do make my program stop reacting on alt-f4 and the "cross".

i am writing a program for a network wich receives messages and the pop's up. i don't want my users to close the program
the mayonly hide it.

canclose := false in the CanClose event doesn't work then windows95 will not shutdown. since the program get's loaded every time the computer boots this is no good.

and i want the program to stop when it gets the message to reboot the system.

thanx for your time
Watch Question


on the MAIN form of the application, set biSystemMenu (under BorderIcons) to FALSE, this will disable closing.

Good luck with your project!

Not the solution you were looking for? Getting a personalized solution is easy.

Ask the Experts


thank you very much, for the quick answer...


the cross disappears, but pressing alt-f4 on the keyboard still close the app..
Oh ok! Sorry about missing the Alt-F4 part.

When the main form recieves the WM_CLOSE windows message it's "default" action is just to close the application (if the main form is showing). We need to inhibit this action by "handling" (ignoring) the WM_CLOSE message, thereby preventing the application from shutting down.

In the Private declarations section of the main form, let's declare the message handler:

procedure WMCLOSE(Var: TWMClose);
       Message WM_CLOSE;

now in the IMPLEMENTATION section let's put the actual code to handle the WM_CLOSE message:

procedure TForm1.WMCLOSE(Var Msg: TWMClose);
Msg.Result := 0;   {If you want the app to ignore the close command}

* or *

Form1.Close   {if you REALLY wanted to close it}

Good luck with your project!
Access more of Experts Exchange with a free account
Thanks for using Experts Exchange.

Create a free account to continue.

Limited access with a free account allows you to:

  • View three pieces of content (articles, solutions, posts, and videos)
  • Ask the experts questions (counted toward content limit)
  • Customize your dashboard and profile

*This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.


Please enter a first name

Please enter a last name

8+ characters (letters, numbers, and a symbol)

By clicking, you agree to the Terms of Use and Privacy Policy.