/* $XConsortium: README /main/3 1996/07/15 14:02:47 drk $ */
README for the DNDDemo and simpledrop.

    This directory contains the demos illustrating typical usage of
    the drag and drop features.  "simpledrop" is a minimalist demo,
    helpful in showing how to get started in drag and drop without
    too many special effects.  "DNDDemo" uses most of the tricks
    available in drag and drop to provide drag over and drag under
    effects.

simpledrop
----------

    The program simpledrop is a minimal drag and drop demonstration.
    It displays a scale widget and a drawing area.

    To use,  startup the program,  set the scale to a value and then
    use BTransfer to drag the scale value.  Drop the scale value into
    the drawing area labelled "drop_here" and the number will appear
    at the drop spot.

    In addition,  you can copy the numbers in the drawing area around.
    Press BTransfer on one of the numbers and then drop somewhere else.

DNDDemo
-------

    This demonstration program uses the Uniform Transfer Model in
    Motif 2.0.

    When the demo comes up, it does not have any valid drop sites. It
    comes up with different color rectangles which act as drag sources
    for dragging the colors around. You can create the drop sites as
    follows:
        Move the pointer into the drawing area (with white background).
        Press MouseBtn1 and drag. You will see the rubberbanding effect.
        Release MouseBtn1 after dragging some distance. A rectangle
        will appear with one of its corners corresponding to the point
        of MouseBtn1 press, and the diagonally opposite corner
        corresponding to the point of MouseBtn1 release. The rectangle
        comes up filled with black by default. You can create any number
        of rectangles like this.

    To initiate a drag, you move the pointer over to the drag source,
    press BTransfer (which is MouseBtn2 by default), and start dragging.
    Immediately, you will notice that the cursor changes to a painter's
    palette in the same color as the color rectangle from which the
    drag is initiated.

    The rectanlges inside the drawing area that you created will act
    as valid drop sites for colors. You can test this by, for example,
    initiating the drag from the yellow color rectangle, dragging over
    to one of the rectangles inside the drawing area, and releasing
    BTransfer.

    While you are dragging, you will notice several things.
    When you are dragging over root window, the dragicon consists of
    only the painter's palette. When you drag over parts of the
    drawing area where there are no rectangles, you will notice that
    the dragicon changes to include a "DO NOT ENTER!" sign on top of
    the painter's palette; when you are dragging over any of the
    rectangles inside the drawing area, you will see that the
    "DO NOT ENTER!" sign gets replaced with a painter's brush.

    To attempt a drop, you will release BTransfer. If you release
    BTranfer with the pointer over any part of drawing area outside
    of the rectangles, or anywhere on the root window, you will see
    that the dragicon snaps back to the point of drag initiation,
    and disappears. This is an indication that the drop you
    attempted was a failure. On the other hand, if you release
    BTransfer with the pointer over any of the rectangles inside
    the drawing area, you will see that the dragicon melts into
    the background and disappears; this indicates that the drop
    you attempted was a success. Also, when the rectangle on which
    the drop was attempted, gets filled with the color that was
    being dragged around (yellow, in our example).

    The rectangles inside the drawing area themselves act as drag
    sources. You can initiate the drag with the pointer on any
    rectangle, and you will notice that the cursor changes to
    a rectangle (either of the same size or a smaller size depending
    on X cursor size constraints). You can drag a rectangle from
    one place and drop it onto a new place inside the drawing area.
    The rectangle gets physically moved to the new position. If,
    on the other hand, you want to copy the rectangle to a new
    position, you can use the appropriate modifier key while dragging,
    and/or at the time you attempt the drop (<Ctrl> is the modifier
    key for copy in the current implementation). When you drag
    a rectangle with no modifier key pressed or with <Shift>
    pressed, you will notice that the solid rectangle from where
    you initiated the drag gets replaced by a hollow rectangle with
    dotted-line borders. It will continue to be this way, for
    the duration of the drag or until you press the <Ctrl> key,
    which will change the operation to Copy; at which time it will
    regain its original solid form.

    A couple of other things to note. Anytime during dragging, you
    can cancel that drag by hitting the Cancel key. Also, during
    dragging, anytime you hit the Help key, you will get a dialog
    giving you some information about whether the drop will
    succeed, what are the drop operations possible, etc.