⤷ Hide the form caption bar

First af all, override the "CreateParams" method of your Form, by declaring this in either your Form's protected or public section:
procedure CreateParams(var Params: TCreateParams); override;
Then, in the actual CreateParams method, specify something like this:

procedure TForm1.CreateParams(var Params: TCreateParams);
  inherited CreateParams(Params);
  with Params do
    Style:=(Style or WS_POPUP) and (not WS_DLGFRAME);
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