Screenshot capture in 2.5.8 windows client?

How do I enable/use screenshot capture in v2.5.8 windows client? In a chat window I click on the screenshot capture icon and the pointer changes to a plus sign. I then click on the window border of the window I am trying to screen capture and send to a recipient but nothing is sent/received.

Thanks

You need to click on the desktop and outline the area you want to send. If you want to send the entire screen click and hold in the upper left corner and drag to the lower right corner. It is a lot like image editing when you want to crop an image.