Are you possibly using a higher than normal font size (High DPI) to make your text appear bigger with high resolution on a large monitor? If so, try this -- right click on either the main executable or the shortcut to the program and select "Properties". Go to the "Compatibility" tab and check the last of the settings, to ignore High DPI scaling. Then try the game and see if that works.
If it does not, I suggest you contact Mark. That's the only solution I know to this kind of issue. I have it with games that sometimes only show me about a quarter of the screen (blown up) unless I set that parameter.
OkAY I set it smaller and I can now use PCstitch. But it makes everything on my toolbar too small to read. So, I gues that I will just have to make it smaller when I am using PCS and then put it back when I am finished.