Today I learned a cool feature of Dolphin in that I can paste an image from my clipboard using Ctrl + V, and it will ask me for a filename and Data format, e.g. PNG.

However, when the file is created it is not given an extension, e.g. myimage.png. This is fine on Linux, as it uses metadata of the file to determine that it's a PNG. Windows and maybe other operating systems need a file extension to determine how to open it. So if I was to send this to a user that uses Windows, they would not be able to open it.