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3.3 Known Problems

There are no problems known with the interpreter in text mode.

As for execution as an applet in a Web browser, we have tested the interpreter with Netscape Communicator 4.6 on Linux and Windows98 and with Microsoft Internet Explorer on Windows98. All versions exhibit various problems.

Communicator: No Focus
When returning to the page embedding the interpreter (after having followed a link or having pressed the Back or Forward button), the applet may not be able to regain the focus.

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

Internet Explorer: Applets Reloaded
When returning to the page embedding the interpreter (after having followed a link or having pressed the Back or Forward button), the applets are restarted (i.e., they do not preserve their previous state).

This seems to be a feature of the Internet Explorer. Do not leave the page if you do not like this.

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

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

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

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

Communicator and Explorer: Java Problems
Several Java and AWT bugs have required workarounds in the interpreter (security violations when using inner classes, wrong handling of end of line conventions, and others).

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


Maintained by: Wolfgang Schreiner
Last Modification: July 13, 1999

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