Dragging an jpg file from the Desktop onto an open Impress files does not result in the image being pasted into the Impress file.  Instead, it opens in a new Draw Document.

To reproduce:

Place a jpg file on the desktop (or some other easily accessible location)
In OO, open a new Impress document
Drag the jpg onto the Impress document: the Green circle with a + in it will appear, indicating that the image can be pasted.
When dropping (i.e. releasing mouse or trackpad), however, the image does not appear in the Impress document, but opens in a new Draw document.