Inaccessible value from control on embedded child form (Delphi, Firemonkey)

  

I am new to Firemonkey (using RadStudio 10.3.2), and I am trying to update a listbox control on an embedded child form. However, when I try to access any of the properties of the listbox (ListBox1), they show up as “Inaccessible value.” I’m pretty sure that I am missing something very simple. I appreciate any and all help! Thank you!

I have made the following, simplified application, to illustrate my issue.

Project1 Application Initialization:

program Project1;

uses
System.StartUpCopy,
FMX.Forms,
Unit1 in ‘Unit1.pas’ {Form1},
Unit2 in ‘Unit2.pas’ {Form2};

{$R *.res}

begin
Application.Initialize;
Application.CreateForm(TForm1, Form1);
Application.Run;
end.

Unit1.pas:

unit Unit1;

interface

uses
System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,
FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs,
FMX.Controls.Presentation, FMX.StdCtrls;

type
TForm1 = class(TForm)
Panel1: TPanel;
Button1: TButton;
procedure FormCreate(Sender: TObject);
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
procedure EmbedForm(AParent:TControl; AForm:TCustomForm);
end;

var
Form1: TForm1;

implementation

{$R *.fmx}

uses Unit2;

procedure TForm1.FormCreate(Sender: TObject);
begin
// Embed Scenarios Form
EmbedForm(Panel1, TForm2.Create(Self));
Panel1.Visible := true;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
data_strings: array of string;
begin
// Assign strings
SetLength(data_strings, 2);
data_strings[0] := ‘Hello’;
data_strings[1] := ‘World’;
// Load strings
Form2.ListBox1.Items.Add(data_strings[0]);
Form2.ListBox1.Items.Add(data_strings[1]);
end;

procedure TForm1.EmbedForm(AParent: TControl; AForm: TCustomForm);
begin
while AForm.ChildrenCount>0 do
AForm.Children[0].Parent:=AParent;
end;

end.

Unit2.pas:

unit Unit2;

interface

uses
System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,
FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs, FMX.Layouts,
FMX.ListBox;

type
TForm2 = class(TForm)
ListBox1: TListBox;
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form2: TForm2;

implementation

{$R *.fmx}

end.

The Form2.ListBox1 properties are inaccessable to the code on the main form–see the Button1Click event. I have the parent form (Unit1) using the child form (Unit2).

I am at a loss as to why an enabled, visible component is inaccessible. My modal forms never had this issue, so I think it has to do with the embedded child form.

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