Pick-and-drop is one of Eiffel Software's exclusive technologies and is provided by EiffelVision. In EiffelStudio it allows you to send data easily from a component of the interface to another.
You can pick every reference to a development object (like a class, a feature or an execution object) with a single click on the right mouse button. Then as you start moving the mouse around - not pressing any of its buttons - a pebble tracks the cursor position, and a line continuously connects the pebble to the object's original position. The pebble's shape indicates the type of the development object that you picked (oval disk for a class, cross for a feature, folder for a cluster...).
You may terminate this situation in either of two ways:
Right-clicking when the pebble is crossed will only stop the pick-and-drop because the component you are hovering with the mouse does not accept your development object. For a class, a not droppable pebble looks like this: