I built a simple Delphi program to test two solutions provided by Martin Schneider on StackOverflow here:

Enabling TWebBrowser High DPI support

… but when the program is dragged to a monitor scaled to 175%, the page content remains unscaled.

Here’s my code for Martin’s “Solution 2”:

unit Unit1;

interface

  uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes,
  Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs, System.IOUtils,
  Vcl.StdCtrls, Vcl.ExtCtrls, ShellAPI, Vcl.ComCtrls, Vcl.ToolWin, System.StrUtils,
  ShlObj, System.UITypes, Vcl.OleCtrls, SHDocVw,
  Winapi.Mshtmhst;

  type
  TDpiAwareWebBrowser = class(TWebBrowser, IDocHostUIHandler)
    strict private
      // IDocHostUIHandler "override"
      function GetHostInfo(var pInfo: TDocHostUIInfo): HRESULT; stdcall;
  end;

  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
  private
  public
  end;

  var
  Form1: TForm1;

implementation
  {$R *.dfm}

  const
  DOCHOSTUIFLAG_DPI_AWARE = $40000000;

function TDpiAwareWebBrowser.GetHostInfo(var pInfo: TDocHostUIInfo): HRESULT;
begin
  // original code from TWebBrowser.GetHostInfo
  pInfo.cbSize := SizeOf(pInfo);
  pInfo.dwFlags := 0;
  pInfo.dwFlags := pInfo.dwFlags or DOCHOSTUIFLAG_NO3DBORDER;
  pInfo.dwFlags := pInfo.dwFlags or DOCHOSTUIFLAG_THEME;
  pInfo.dwFlags := pInfo.dwFlags or DOCHOSTUIFLAG_DPI_AWARE; // NEW added flag
  Result := S_OK;
  //ResizeScrollBars; // will be called by subsequent routines anyway.
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  var wb:= TDpiAwareWebBrowser.Create(Form1);
  TWinControl(wb).Parent:= Form1;
  wb.align:= alClient;
  wb.Navigate('https://google.com');
end;

end.

In this screenshot, you can see the title bar of the test program is properly scaled for a monitor set to 175%, but the TWebBrowser based component isn’t:

Here’s a screenshot showing the monitor’s scaling:

I also implemented Martin’s “Solution 1” as shown in this screenshot of the Windows registry:

I’m using Delphi 11:

I’m developing on Windows 10 inside a VMware Workstation 16 Pro virtual machine.

What am I missing?