Providing Visual Feedback with Freedom of User Action for Slow Tree View Expansion
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2005-Mar-30
Johnson, DK: AUTHOR [+2]
Disclosed is a technique that provides the visual feedback that the user needs in order to know that a slow tree view expansion is underway and allows the user the freedom to fully interact with the window in other areas while waiting for that expansion to occur.
Providing Visual Feedback with Freedom of User Action for
a technique that provides the visual feedback that
the user needs in order to know that a slow tree view expansion is
underway and allows the user the freedom to fully interact with the
window in other areas while waiting for that expansion to occur.
The tree view
of the OS/2* Presentation Manager* (PM) container
control is used to display hierarchical relationships between the
objects in the container. Each node in the tree can have children;
if it has children, it can be displayed as expanded or unexpanded.
bitmap displayed to the left of each record denotes
whether the record has children and whether it is expanded. If it
has no children, no bitmap displays. If it has children and is
expanded, the bitmap is an encircled "-". If it has children and is
not expanded, the bitmap is an encircled "+". This use of the bitmap
is well known and understood by users of the operating system.
occurs, however, in very dynamic applications that
incur significant performance penalties in instantiating each record
in the container. In order to avoid delays in initially displaying
the window with the container, only the top-level records are
instantiated. PM is told that the top-level records have children,
so that the proper bitmap is displayed beside the record, but the
children are neither instantiated immediately nor part of the
When the user
clicks on the "+" bitmap to expand a node, the
application has to instantiate all of the next level children for
that node and add them to the container so that they can be
displayed. This can take a considerable amount of time. During the
period between the user clicking on the bitmap and the expansion of
the node, feedback should be provided to users to inform them that
work is going on and that the node will soon expand.
technique used by other applications is to lock the
window and change the mouse pointer to the clock to indicate that the
application is in a wait state until the work completes. This is not
a usable solution, because it prevents the user from interacting
elsewhere with the window. While waiting for previous expansions to
occur, the user should be allowed to click on the bitmap of other
records to expand them as well or to double-click on a record to open
it. Users should also be allowed to close the window if they decide
to work elsewhere in the application. All of these usability
considerations are negated by an application that locks the window
until the expansion is completed.
is to transform the visual appearance of the
record being expanded so that it is intuitive to the user that an
expansion is in progress. It is not necessary to modify the mouse
pointer and thus not necessary to lock the window in any way to
modify the appearance of a re...