screenshot ability not always available

You can use Shutter to take screenshots from context menus.

$ sudo apt-get install shutter

I also found myself experiencing this problem, but I found a way around it.

For this I used the screenshot application that already comes with the default installation.

To do so, go to Acessories → Screenshot, and set a timer that will start counting after pressing the buttom in the application window. While the timer is counting, go to the desired place and use right-click, then the screenshot should be taken.

Lastly: screenshots are saved in the Images directory in the user's home.

Personally, I like the idea of having the screenshots saved there automatically, specially since I usually press the screenshot key accidentally while having an important item or text in the clipboard. So if the clipboard would be automatically populated by the screenshot, I would lose the important item or text.

Having to do too many workarounds does complicate the use of the OS, lets try to keep it intuitive to not slow the learning curve...

The timer one is a good workaround though.

Actually saving to a file is the most likely thing you will do next (so that feature is good, *) - but in some cases you can want a better screenshot instead and you have to go hunt for the image you want to keep which is a pain (if that happens too often you may need to let us use a save screenshot key or a delete last key!). *In windows I preferred to save to a GIF to cut down on some of the colour information and file size (GIF is 256 colour, which works good provided it does not dither).