In a scrollable user interface window including two or more panels, a single scroll bar scrolls all of the panels. Panels move in lock-step with one another at certain times, but not at other times, depending on whether the lock-step scrolling would cause blank areas to be displayed. If the user's scroll commands would result in a blank area of a panel being displayed, the scroll command is not performed; rather, the panel remains frozen in its current position, even while other panel(s) do scroll. Thus, according to Apple, the present invention ensures that useful content is displayed at all times in all panels, and no screen real estate is wasted due to scrolling operations.
Here's Apple's background and summary of the invention: "Scrolling is a well-known feature of graphical user interfaces. When the size of a document being displayed in an on-screen window exceeds the size of the window, scrolling allows a user to control which portion of the document is shown at any given time. Typical user interface elements for controlling scrolling operations include horizontal and vertical scroll bars, scroll "thumb" widgets that move within the scroll bars to indicate the current position of the viewable area within the overall document, and arrow buttons for incrementally shifting the viewable area by some predetermined amount (such as line-by-line, or page-by-page). The user can shift the position of the viewable area in any of a number of different ways. The user can drag a thumb widget to any position within its scroll bar to shift the viewable area to a location corresponding to the new widget position. The user can also click within a scroll bar at a location other than the current thumb widget position to shift the viewable area by some predetermined amount (such as by page). Or the user can click on arrow buttons to shift the viewable area by some smaller predetermined amount (such as by line). If the user has a mouse that includes a scroll wheel, the user can turn the wheel to scroll on a line-by-line basis as well. Keyboard control may also be provided. Other techniques are also known in the art for causing the scroll position to change.
"In some cases, scroll bars are provided for scrolling in two dimensions--a horizontal scroll bar and a vertical scroll bar. In other cases, only one dimension of scrolling is needed, and only one scroll bar is provided.
"The present invention provides an improved mechanism for scrolling multiple panels. Panels move in lock-step with one another at certain times, but not at other times, depending on whether the lock-step scrolling would cause blank areas to be displayed.
"The user need only manipulate one set of scroll controls. Each panel scrolls in response to the user's scroll commands normally, except when the indicated scrolling operation would cause a blank area to be displayed. If the user's commands would result in a blank area of a panel being displayed, the scroll command is not performed; rather, the panel remains frozen in its current position, even while other panel(s) do scroll. Thus, the present invention helps optimize the use of available screen real estate.
"In addition, the present invention allows the user to scroll useful information in the shorter panel back into view faster, since he or she is not forced to wade through a long blank area before getting back to a section where content is displayed."
The inventors are Scott James Forstall, Gregory N. Christie, Kevin John Tiene, Donald Dale Melton, Stephen Lemay, Wayne Russell Loofbourrow, Jessica Kahn and David Hyatt. The graphic below depicts an example of a browser window employing scroll bars.
