erasing objects from dynamic windows

["Dennis L. Doughty" <doughty@scrc-yukon.arpa>]

    Date: Wed, 27 Jan 88 16:33 AST
    From: C. Ann Dent <Ann@DREA-PHOENIX.ARPA>



    I want to display an object upon a dynamic window such that its display
    remains visible whenever the viewport is scrolled to show some of the
    area where the object was displayed.  However, I would like to be able
    to erase the display of that object at a later time (such that its
    display will no longer visible even if the viewport is scrolled to show
    the location where it was originally displayed).

    This seems like such a trivial task that I suspect the solution must be
    obvious.  Any suggestions or pointers? 

	    Ann

    P.S.  By the way, the size of the display of object may be larger than
    the size of the viewport to the dynamic window.  Also, the location of
    its display may lie totally outside the boundary of the viewport of the
    window when the object is originally displayed. 
    -------

What do you mean by "display remains visible"?  Are you asking for the
capability to ensure that if a portion of the given presentation is
somehow scrolled into the viewport, then all of the presentation must be
scrolled in, or are you asking for the ability to somehow "lock" a
window so a given presentation doesn't scroll off?

To remove a presentation, you can 

(send your-window :erase-displayed-presentation your-presentation)