hi golitan,
pretty simple way to solve this issue, is to start with a higher resolution
Black Ink will automaticly start with the size and format of the paintarea @ 150dpi/zoom 33% ...thats three times bigger than the resulution shown on your display...pretty big i think
or go and create a file with your own resolution setting like 10240pix²/72dpi... thats the highest resolution i can set (800MB)^^ maybe you can get higher resolutions with bigger GPUs?