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3.4 Known Problems

There are no problems known when the evaluator runs in text mode or in window mode or in applet mode with the JDK appletviewer.

As for execution as an applet in a Web browser, we have tested the evaluator with various versions of Netscape Communicator on Linux and Windows and with Microsoft Internet Explorer on Windows. There are several problems caused by Java/AWT bugs in these browsers.

Communicator: No Focus
When leaving a page embedding the evaluator applet (by following a link or pressing the buttons Back or Forward), on return to this page the applet may not be able to gain the focus again.

This seems to be due to an error in AWT. Do not leave the page (use the middle mouse button to open a link in a new frame) or press the keys Shift+Reload to reload the applet.

Internet Explorer: Applets Reloaded
When leaving a page embedding the evaluator applet (by following a link or pressing the buttons Back or Forward), the applets are restarted (i.e., they do not preserve their previous state).

This is apparently a feature of the Internet Explorer. Do not leave the page if you want to have the applet state preserved.

Communicator (some versions): Browser Frozen
When starting the execution of a command in the evaluator, the browser freezes until the execution of the evaluator has terminated.

This seems to be due to an error in multi-threading. Wait until the corresponding execution has terminated or kill the browser.

Communicator: Console Messages
Sometimes error messages appear in the Java console when (re)loading a page that embeds the evaluator.

This behavior seems to be due a Java internal problem; apparently it does not indicate any significant troubles. Ignore the messages.

Communicator and Explorer: Java Bugs
Several Java bugs have required workarounds in the evaluator (most notably security violations when using inner classes and wrong handling of end of line conventions).

Since we have found workarounds, one should not encounter these problems any more.


Maintained by: Wolfgang Schreiner
Last Modification: September 16, 2004

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