The reason the majority of the VPLab screens are black is that it is much quicker to refresh the screen, and the graphics side of the simulations can run more smoothly. If you want to print part of a screen, the semi-satisfactory way to do this is as follows:
Press “Shift-Print Screen”, and then open Microsoft Paintbrush (Normally “Start-Programs-Accessories-Paint). Now press “Ctrl V” (or right click and select ‘paste’). The entire screen should have dumped into the Paint Brush window.click on the select rectangle button of paintbrush to box the part of the image you want. While it is still boxed, click on the ‘Image’ button at the top of the Paint Brush window and select ‘invert colours’ All the black should have turned to white, and all the colours are unrecognisable! This might be good enough for your purposes, but if you want to recover the original colours carry out the next step.
Now click on the ‘fill with colour’ button on the left hand side of the Paint Brush Screen (it looks like a bucket of paint), and select the black colour at the bottom left hand side of the screen and paint all the white back to black again! Then select ‘Edit – Select all’ (or Ctrl A) and then ‘Image-invert colours’ again in order to return back to the original colours (without the black). Notice that the screen pieces contained inside hollow letters may need some special attention!