A timed dialog -- auto-closing dialog box

Suppose that you want a dialog-box that closes automatically, say after 15 seconds.
You want to call that dialog by clicking a button on your main form:

void __fastcall TForm1::Button1Click(TObject *Sender)
{
  TimedDlg.Execute("Warning", "Invalid entry in edit-box AGE.
                    Please correct.");
}

Here's a quick and simple solution, made with C++ Builder:

1. Add a new form to your project and name it TimedDialog.
2. Save the new unit as TimedDlg.
3. Set the form's BorderStyle property to bsDialog.
4. Add three components:
   - a TTimer. Set its property Interval to 15000 (that's 15000 milliseconds). Or set it to less -- for
     example, 5000 for 5 seconds. Set the timer's property Enabled to False.
   - a TMemo.
   - a TBitBtn. Set its property Kind to bkOK.
5. In TimedDlg.h, add a line under public: as follows:

   public:		    // User declarations
     __fastcall TUserDialog(TComponent* Owner);
     void Execute(String Title, String Contents);

6. In TimedDlg.cpp, add the following function implementation at the end of the unit:

   void TTimedDialog::Execute(String Title, String Contents)
   {
     Caption = Title;          // set the caption of the form
     Memo1->Text = Contents;   // set the text of the memo
     Timer1->Enabled = True;   // start the timer
     ShowModal();              // show the form
     Timer1->Enabled = False;  // stop the timer
   }
   

7. Double click on the TTimer component and complete the event handler as follows:

   void __fastcall TTimedDialog::Timer1Timer(TObject *Sender)
   {
     Close();   // close the form 
   }

8. Select Unit1.cpp and in the menu, select File / Use unit..., next select TimedDlg.cpp.
9. Save all and test your program.

How does it work?

• The function Execute shows the UserDialog form in a "modal" way, that means: the window will open on top of the other window(s) and the application does not continue before UserDialog is closed.
  A timer is started.
• If the user clicks the OK button, the form is automatically closed, because the button's Kind is bkOK.
• If the user doesn't click the OK button before the timer fires, the form is closed "automagically".