Access Violation using TVCLStylesPreview in Alexandria (with solution)

[jdorlon-Quest]

Running the VCL Styles Preview demo under Delphi 11 Alexandria will result in an access violation.

The solution is to change this, in VCL.Styles.Ext, around line 93

  TSourceInfo = record
    Data: TStyleServicesHandle;
    StyleClass: TCustomStyleServicesClass;
  end;

to this

  TSourceInfo = record
    Data: TStyleServicesHandle;
    StyleClass: TCustomStyleServicesClass;
    DesigningState: Boolean;
  end;