In this image you can see the blueprint preview going over the left edge of the tooltip:

In this image you have to look close but the preview goes over the top left corner of the tooltip:

I run the x64 Linux version of Factorio. Although I have a number of mods installed in that game I doubt that they are causing this problem. I didn't include a save since mine is ~46 MB (nearly all in level.dat). If you have difficulty reproducing the bug I can try and upload the save someplace.
Steps to reproduce:
1. Make a blueprint large in both dimensions such as an entire endgame base.
2. Look at the blueprint tooltip and see the preview going over the left and or top edge.




 It was stupid computation error.
 It was stupid computation error.