JDK: 1.2, 1.3
OS: Solaris, Windows
Locale: All

According to JDK1.2's api specification, programmer can set JFrame's contentPane
to transparent, using setOpaque(false). Then there will exists graphics painting
problem. That is, if in eventDispatch thread, we change the location of one
JComponent of the contentPane, the contentPane does not clear its previous
invalid region that the JComponent occupied, but if the contentPane is opaque,
it will use fillRect(getBackground()) to fill the previous invalid region.

See attached program to show this problem.

Run the attached program, press the button and see what will happen.


jim.hu@prc 1999-08-05