This section presents some of the problems related to the functionality of the text pane display. These problems were either reported directly by the knowledge engineers or were discovered by studying the knowledge engineers as they worked.
Problem: The user often needs to quickly view information about some of the text objects in a text pane. (Text objects are any of the objects that are highlightable in the text pane. See Section 2.1.3 for a more detailed description.)
Solution: A point-and-click mechanism was developed for viewing the knowledge base. A left mouse click on any text object in a text pane causes the frame for that text object to display in the least recently used text pane, i.e. the text pane that has the longest time interval since it was last used. The middle mouse click was added later so that the frame for the text object's address could be similarly displayed.
Problem: Sometimes, the least recently used text pane contains a frame that the user still needs.
Solution: By choosing the "Lock" option in the text pane menu, the user can lock the text pane so that the text pane is ignored by the least recently used algorithm.
Problem: The user wants the quick display feature to replace the frame in the text pane that contains the text object, rather than the least recently used text pane.
Solution: The <control>-Left and <control>-Middle clicks were added to provide the same functionality as the Left and Middle clicks, except that the frame is displayed in the current text pane.
Problem: The user generally doesn't want to see the contents of the entire frame.
Solution: The display generation mechanism was changed so that it used plans, rather than a fixed generation mechanism. These plans organize the slots of a frame into groups. The user can choose which of these groups to display via the menu produced by the "Set Display Options" choice in the text pane menu.
Problem: The user wants to see values that can be inherited from other frames in a frame's hierarchy.
Solution: In general, the values that are displayed in text panes are values that are stored locally on the frames. Since inheritance is an expensive operation and produces voluminous information, inherited information is not usually displayed. The current method requires the user to enter the addresses of the values he/she wants to see in the "Inheritance Subaddrs" field of the menu produced by the "Set Display Options" choice in the text pane menu. The values that are inherited will appear surrounded by square brackets.
Problem: The user sometimes gets lost when navigating inside a text pane. Generally, the user is unable to understand some annotation information since he/she looses track of the indentation depth, which is used to differentiate the nesting level of the annotations.
Solution: The user can ask for the address of any text object by clicking Right on the selected object. The address appears in a permanent window, so the user can refer to it while continuing to work in the text pane.
Problem: The user may be looking for a specific address in the text pane, but cannot find it because he/she gets lost in the indenting.
Solution: The user can use the "Goto Slot" option on the frame, slot, or annotation menus to scroll to the desired address.