Question

Is it possible to display an Icon obtained from an external Handle, as the Image of my Node in Virtual Stringtree? The Node’s Data contains the HWND.

Answer 1

I would use ImageList assigned to your VT’s Images property and OnGetImageIndex event.
Here’s how to fill the image list using WM_GETICON.

procedure TForm1.Button1Click(Sender: TObject);
var IconHandle: HIcon;

begin
  IconHandle := SendMessage(123456, WM_GETICON, ICON_SMALL2, 0);
  ImageList_AddIcon(ImageList1.Handle, IconHandle);
end;

And for example pass the 0 image index to the VirtualTreeView.

procedure TForm10.VirtualStringTree1GetImageIndex(Sender: TBaseVirtualTree;
  Node: PVirtualNode; Kind: TVTImageKind; Column: TColumnIndex;
  var Ghosted: Boolean; var ImageIndex: Integer);
begin
  ImageIndex := 0;
end;