I have recently switched from Windows to Linux (mint 18.2 with KDE, using Dolphin as file manager). I have noticed that when using the "open file" dialog (or upload file) in any external application you can't choose a remote url as source from the file
In windows, if i paste an url as file source for file upload it gets uploaded just fine, here the "open" button is disabled (i know the image i typed does not exist but it's disabled even with an existing image)
Is there some way to do this on linux too? since i often upload images from the web into other websites this feature was very handy
Dolphin does not support web pages, the web browser has been launched
: Konqueror was then launched and the image appeared in it. This is not the same as your Open dialogue, but it suggests that your dialogue may work on current releases. My Dolphin release is 14.12.3 and Konqueror is 4.14.16.