Ok, capture, but stay invisible...

As asked by many user, I've added a new capture mode that allows users to retrieve "alpha channel" info of windows with transparency elements (borders, shadows, glass panels). It's quite a workaround and a bit rude, but for the most part it works as expected: to recover alpha I simply take two screenshots of the window, one with a black bakground, the other with a white one. This approach is more or less the same illustrated by Ian Griffiths in his blog (thank you for the idea and the explanation...). This mode must be enabled in settings, otherwise Snappy will continue to use default capture mode.

That said, in this new version I'va also added useful features (well, at least for me...):

• Open with external app
• Selection tool in screenshot editor (currently only rectangle selection, but list will grow...)
• Add images from file system
• Cut/paste screenshot selection