To differentiate between a double-click on a thumbnail and a double-click on white space in the ImageEnMView control, I tried the TImageEnMView.MouseDownThumbIndex information in the TImageEnMView.DblClick event-handler:
procedure TformMain.ImageEnMView1DblClick(Sender: TObject);
begin
CodeSite.Send('ImageEnMView1.MouseDownThumbIndex', ImageEnMView1.MouseDownThumbIndex);
end;
This works ALMOST (!) correctly: However, when double-clicking WAY BELOW the last thumbnail row, MouseDownThumbIndex gets a positive result instead of -1!
https://app.screencast.com/SJyifkWakas1X