When working on objects in Draw/Impress and having zommed in to do so, is is
easy to lose orientation. It would be very helpful to visualize the visible part
of the view with an overlay object on the corresponding PagePreview in the
PagePane. When working zoomed, this would give orientation with a single look
and add useful functionality for the page pane (especially for draw).

Using an overlay object this would need no content repaints and be cheap. Only
paint the zoomed area clipped with the page margins, so nothing would be
displayed in Impress default view (whole page). For visulaisation, a dashed line
(like for selection frames) or alternatively a selection frame (selection filled
transparently with the user's choosen selection color, see SC selection) could
be used.

An extra would be to be able to move that area with the mouse to change the
zoomed area, but even without this it would be a nice usability feature.