Capture pop-up menu items with Snipping tool- Windows 10
Windows 10 now allows the capture of menus and sub-menus through the standard snipping tool.
This is done by delaying your capture speed when screenshotting images.
Step One: open up snipping tool from the start menu and select Delay. You will then select your delay time between 0 to 5 seconds.
Step Two: After delay time is selected, you can now select the form of screen shot you would like to complete by clicking the tiny triangle 
next to New.
Step Three: You are now ready to take a screen shot. Click on New and you will now have up to 5 seconds to complete your screen selection and the screenshot will be created. Your screen will fade out like the following image until the screen selection is complete. Final step is to ensure to properly Save your image.
You have now successfully screenshot your popup window.