Intermittent display problems in JRE 7

[Mickey Segal]

I’m new to this group, but have been a member of Apple’s Java-Dev group since the late 1990s.  The Macintosh users of our large medical diagnosis applet have begun pointing out intermittent display problems in JRE 7, and we are able to reproduce these problems.  It is not clear with which version of Java the problem started; we had not been doing much Macintosh testing recently since everything seemed to be fine.  We have seen no similar issues on Windows. 

 

The behavior we see is that screen re-draw stops intermittently, leaving parts of the screen displaying the previous screen’s contents.  The problem is not component by component, instead it seems to involve screen regions.  Forcing a screen redraw by widening the Frame in which the applet runs or putting the mouse over a component with a ToolTip causes the screen to be redrawn correctly.   

 

Is this a known problem, or do I need to reproduce it in a tiny applet to get this fixed?  Is there some simple workaround?  I’ve tried various invalidate / validate approaches without success.  

 

During the era in which Apple did its own version of Java and kept bug reports secret, I posted a large number of test applets used for bug reports by me and others at http://www.segal.org/java/.  I’ve started looking through those applets to see if I already have a test applet that illustrates the current problems.  I’ve quickly found one bug that illustrates a different display problem in which random contents of the browser cache get inserted into the applet display area.  This is a different problem from the main problem I’m trying to solve, but I thought I’d post that for comment before submitting a bug report since I’ve found that other people on groups such as this often have comments and suggestions that improve a bug report.  This applet, entitled “Applets on MacOS over 800 pixels high have display problems”, is at www.segal.org/java/refresh.  I’d be grateful for comments on this, and will submit an official bug report.  

 

But my main goal is to solve the screen re-draw issue and I’d appreciate feedback from others as to whether this is a known issue.  So far our only workarounds are to tell people to force a screen re-draw or switch to Windows.  However, I imagine we are not the only ones seeing this problem and we should be able to get Java on the Macintosh working better than that.