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3.4 Known Problems

The toolkit was developed and tested under Linux, Solaris, Windows NT 4.0 using JDK 1.0.2 (Linux, Solaris), JDK 1.0.3 (Linux), JDK 1.0.4 (Solaris), Netscape Navigator 3.02 (Linux, Solaris), Netscape Communicator 4.03 (Linux, Solaris, Windows NT 4.0). I know about the following user interface problems but do not know how to fix them because of bugs or limitations (features?) of the different versions of the Java AWT.

JDK PopUp Windows in Applets

All versions of JDK aparently have serious bugs in class Window in applet mode, which makes it impossible to determine the appropriate size of a popup window and to display the contents such that they are visible under different browsers. The applet warning string is displayed at different edges of the window (top, bottom, left) by different browsers without adjusting the window size or coordinate system.

DAJ for JDK 1.0 uses a hack that should make the contents visible under most browsers (JDK 1.0 appletviewer, Netscape 3.0/4.0 under Linux, Solaris, and Windows NT 4.0) but yields oversized windows. DAJ for JDK 1.1 uses a hack that makes the contents visible under JDK 1.1 appletviewer and gives even more ugly results.

JDK 1.1 Scrolling

In JDK 1.1, positioning scrollbars apparently behaves differently from JDK 1.0, therefore the DAJ source is different in both versions. Scrolling the visualization area in an application developed with JDK 1.0 does not work correctly under JDK 1.1 (and certainly not vice versa).

JDK 1.0 X-Server Memory Consumption

In JDK 1.0 under X-Windows, during a visualization run, the memory consumption of the X-Server continuously grows until the visualization is interrupted (by which free memory becomes instantly available again). This may bring especially X-Terminals down to their knees during longer visualization runs.

JDK 1.0 Scrolling in Applets

In JDK 1.0, on various browsers the size of the vertical scrollbar slider does not match the size of the visualization area. In Netscape 4.0 on Solaris, the slider is one pixel too small, in Netscape 4.0 on Windows NT 4.0, the slider is about a frame width too small.

JDK 1.0 PopUp Window Positions

In JDK 1.0 the computation of a component's offsets from its parent component apparently does not work correctly. The pop-up windows do not appear in the specified locations but a few pixels off.

JDK 1.0 Window Resizing

In JDK 1.0, resizing the visualization window returns a zero coordinate in the corresponding event. Thus there is apparently no possibility to determine the correct window position, if the window is resized from the left upper corner. Popup windows appear in wrong places until the window is moved.

JDK 1.0 Window Closing

In JDK 1.0, it is apparently not possible to trigger an action when the user selects the menu item "Close" in a window's frame. The window remains open.

JDK 1.0 Visualization Window in Applets

In JDK 1.0, there is apparently no possibility to determine the position of an applet in absolute screen coordinates. The visualization window thus pops up always in a fixed place.

JDK 1.0 Help Menu

In JDK 1.0 on Linux, setting help menus for menu bars does not work. Thus the help menu is generally added as a normal left-justified menu in DAJ for JDK 1.0.

JDK Scrollbars

In both versions of JDK, it is apparently not possible to determine the height/width of a scrollbar before the component is created to which the scrollbar is attached. Thus the visualization area is a bit smaller than specified by the programmer in both dimensions (the area includes both the horizontal and the vertical scrollbar).

Netscape 4.0 Applet Redraw

Under Netscape 4.0 on Windows, the visualization area of an DAJ applet is sometimes not redrawn when the popup window is closed.

Netscape 4.0 Applet Stops

Netscape 4.0 does not trigger the stop method of an applet when the browser is iconified, thus the visualization window remains open.