The described behavior is not something that could be controlled by the RadEditor.
Firstly, when dragging images, or some text elements into the content area of the editor, a cursor appears because the browser editable functionality allows it. The cursor position, where the dragged element is hovered is rendered by the browser and the RadEditor control does not have control to it.
Also, when the jQerry draggable is used, the elements are rendered as block elements and thus the native browser engine does not recognize them as elements that can be dropped into a content editable area. By that a cursor is not rendered, and by dropping the content is inserted in the initial cursor position of the editor.
You can examine the same behavior even with a simple DOM element like this one:
"width:500px; height:300px; border:1px solid red;"
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