Actually almost every site that supports a feature just to paste a picture from clipboard, for example in a message, and site uploads it right away.
For example, and most important -
https://vk.com
In every other browser I can just copy an image (not url) from anywhere, even from paint in windows or just right after PrintScreen was pressed, and just press ctrl+v when chatting, image will upload and attach to a message. But not in K-Meleon for some reason.
Actually it will work if I will copy an image in Google Chrome and then paste it in K-Meleon, it will work. But not if I will copy it in K-Meleon.