Press Cmd+V or Ctrl+V on an Idea Workspace to paste from another app. A picture, such as a screenshot, becomes an image card and is saved to your image library. A web address becomes a link card, and any other text becomes a note. The card goes where the pointer is, or in the part of the canvas you can see.
Cards copied from a workspace still paste back as cards. Copying them now also puts their text on your clipboard, so it can be pasted into another app.