How to make a screenshot with a Mac keyboard on a Mac that is running Windows 7?
Create a keyboard shortcut with the built-in snipping tool.
Start > Accessories > Snipping Tool > Properties > Shortcut
Click in the Shortcut key
text box and enter your desired key combination.
Windows 7 has a built in screenshot software, its called Snipping Tool.
It can be found on the All Programs > Accessories menu
Fn + Shift + F11 for fullscreen
Fn + Option (Alt) + F11 for active window
Screengrab means to capture any moment you want on your screen. Snipping Tool is not well designed for that purpose. Always be prepared for an alternative when using Microsoft made applications.
Fn + Shift + F11 for fullscreen
Fn + Option (Alt) + F11 for active window
above hotkeys indeed solve the problem, thanks to Sergiy