Just for curiosity, why some parameter like Graphics.DrawPicture ( x as double etc. ) than must have an integer value are declared as double?
Change is coming
ok, but it should has been a reason why was designed like this?
Xojo changed the drawing engine in 2016.4 but they forgot on some places at the documentation to change the parameter datatype from integer to double. You can always use doubles to get more drawing precesion.
Using doubles with 2015r1 allow to get the real asked values (when resizing an image): 200 pixels tall instead of 199 (for example). But, this is just my experience. 
In the past when things were based on a fixed 2D space in 72dpi, and double math were slow, integers made sense, and pixeled lines too. Now the drawing space resolution is variable, and when doing vector drawings or zoom in/out calculations, you get fractions that need to be normalized to the integer space. With direct double values, not anymore. This way, now you even get subpixel values.