A safe way to create a unique instance of a modal VCL form is to use a local variable in an event handler as a reference to a new instance. If you use a local variable, it doesn't matter whether the form is auto-created or not. The code in the event handler makes no reference to the global form variable. Using RAD Studio, the following procedure creates a modal form instance dynamically. It (optionally) removes the second form's invocation at startup.  

Building this VCL application consists of the following steps:

1. Create the project directory.
2. Create two forms for the project.
3. Remove the second form's invocation at startup (optional).
4. Link the forms.
5. Create a control on the main form to create and display the modal form; then write the event handler.
6. Build and run the application.

1. Choose FileNewOtherDelphi Projects or C++Builder Projects and double-click the VCL Forms Application icon. The VCL Forms Designer displays Form1.
2. Choose FileNewOtherDelphi ProjectsDelphi Files or C++Builder Projects and double-click the Form icon. The VCL Forms Designer displays Form2.

1. Choose ProjectOptionsForms. The Project Options dialog displays.
2. Select Form2 in the Auto-create forms list and click [>]. Form2 is moved to the Available forms list.
3. Click OK to close the dialog.

1. Select Form1 and choose FileUse Unit (Delphi) or Include Unit Hdr (C++). The Uses Unit dialog displays.
2. Select Form2 (the form that Form1 needs to reference) in the dialog.
3. Click OK.

For C++, the #include “Unit2.h” directive is added to Unit1.h.

1. Select Form1, if necessary; then, from the Standard page of the Tool Palette, place a TButton on the form.
2. In the Object Inspector with Button1 selected, double-click the OnClick event on the Events tab. The Code Editor displays with the cursor in the TForm1.Button1Click (Delphi) or TForm1::Button1Click (C++) event handler block.
3. For Delphi, insert the cursor just above the event handler block and enter the following statement to define a local variable:

var FM: TForm2;

For C++, enter the following variable declaration:

TForm2 *FM;

4. Insert the cursor in the event handler block, and enter the following code:

FM := TForm2.Create(self);
FM.ShowModal;
FM.Free;

FM = new TForm2( this );
FM->ShowModal();
FM->Free();

1. Save all files in the project; then choose RunRun. The application executes, displaying Form1.
2. Click the button. Form2 displays.
3. With Form2 displayed, attempt to click on Form1 to activate it. Nothing happens. Click the X in the upper right corner of Form2. Form2 closes and Form1 becomes the active form.