Actually you should probably use the windows BOUNDS and NOT top and left
Top and Left refer to the “content area” which excludes the frame
see http://documentation.xojo.com/index.php/Window.Top and http://documentation.xojo.com/index.php/Window.Left
Bound refers to the entire window INCLUDING the frame
http://documentation.xojo.com/index.php/Window.Bounds
The difference ? In many cases very little - but in some very significant
Well if you have a toolbar on the window the content region starts below the toolbar
So using top and left you might place the window in a way that top left are both 0 and the menu bar tool bar etc are off the screen
If you use Bounds as shown in the examples on the page I pointed out you wont do that