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Implementing List Box Insertion Emphasis during Text Drag-Drop Operations

IP.com Disclosure Number: IPCOM000114284D
Original Publication Date: 1994-Dec-01
Included in the Prior Art Database: 2005-Mar-28
Document File: 2 page(s) / 92K

Publishing Venue

IBM

Related People

Johnson, DK: AUTHOR [+3]

Abstract

The OS/2* Presentation Manager* (PM) graphical user interface supplies APIs that enable drag-drop techniques within and between applications. One such use of these APIs is to allow the dragging of text to and from entry fields and list boxes.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Implementing List Box Insertion Emphasis during Text Drag-Drop Operations

      The OS/2* Presentation Manager* (PM) graphical user interface
supplies APIs that enable drag-drop techniques within and between
applications.  One such use of these APIs is to allow the dragging of
text to and from entry fields and list boxes.

      One of the many requirements that the Common User Access* (CUA)
standards place on applications that provide drag-drop is that the
target of the drop must display an indication of where the dragged
object will be placed if the drop takes place.  While the CUA
standards address this issue for the common drag-drop implementation
of dragging icons within a container, the standards do not address
the unique needs of a list box, when the list is the target of a text
drag-drop operation.

      When text is dropped on an unsorted list, the new text should
be inserted at the position in the list following the list item the
mouse was over when the drop occurred.  Due to the size of the mouse
pointer, the possibility of a small font being used in the list, and
the space between adjacent list items, an indicator needs to be shown
for users to always be able to tell exactly where in the list the
insertion will occur.

      While the application could highlight the specific list item
that the mouse is over as the drag takes place, this is not the
information that users need.  Users need to be told where the
insertion will take place, not some ancillary information from which
they can discover that insertion point.

      The best solution for telling the user exactly where the
insertion will occur is to draw a line below the list item that the
mouse is over.  When this list item is not the last in the list, the
line displays between the two list items where the new text will be
inserted.  When the drop will be below the last list item, the line
is drawn directly below the list.  This is exactly what users need to
know, presented in the most obvious and intuitive manner available.

      Drawing a line using PM calls requires having a particular
color to draw it in, however.  Since CUA standards insist that the
users be able to choose any colors for windows and controls, there is
no way to choose a color for the insertion emphasis line and be sure
that it is highly visible against whatever colors users have chosen
for the list box.  This is further complicated, because some list
items may be painted with selection emphasis, using different colors
than those list items that are not selected.

      The solution to this problem of choosing the color of the
insertion emphasis line is to always draw it in reverse video of t...