<AWT Dev> <Swing Dev> [7u-dev] Review request for JDK-8046559: NPE when changing Windows theme

Alexey Ivanov alexey.ivanov at oracle.com
Tue Jul 15 11:03:04 UTC 2014

Hi Anthony, Petr,

Thank you for your review.


On 11.07.2014 9:47, Petr Pchelko wrote:
> Hello, Alexey.
> Looks OK to me too.
> With best regards. Petr.
>> On Jul 11, 2014, at 1:43 AM, Anthony Petrov <anthony.petrov at oracle.com> wrote:
>> Hi Alexey,
>> I skimmed through the changes and they look fine to me. +1.
>> --
>> best regards,
>> Anthony
>> On 7/10/2014 7:59 PM, Alexey Ivanov wrote:
>>> Hi AWT, Swing teams,
>>> Could you please review the backport of JDK-8046559 to jdk7:
>>>      bug: https://bugs.openjdk.java.net/browse/JDK-8046559
>>>      webrev: http://cr.openjdk.java.net/~aivanov/8046559/jdk7/webrev.00/
>>> Changes between jdk9 and jdk7:
>>> I replaced labmda expression in WToolkit.java with anonymous class.
>>> It is the only change from the previous webrev:
>>> http://mail.openjdk.java.net/pipermail/awt-dev/2014-July/008147.html
>>> http://mail.openjdk.java.net/pipermail/swing-dev/2014-July/003657.html
>>> Latest jdk9 webrev:
>>> http://cr.openjdk.java.net/~aivanov/8046559/jdk9/webrev.01/
>>> The information is below is copied from jdk9 review for the sake of
>>> completeness.
>>> Problem description:
>>> When changing Windows themes from a theme with visual styles (Windows
>>> Aero or Windows Basic) to a classic one, NullPointerException could be
>>> thrown from Swing code during component tree validation, or
>>> InternalError could be thrown during component painting.
>>> Root cause:
>>> Windows theme data are accessed via XPStyle and ThemeReader. When the
>>> theme is switched to a classic one, theme handles become unavailable,
>>> and theme data cannot be accessed any more. The change in theme is
>>> posted to EDT; at the same time, the UI often needs to repaint before
>>> the theme change is completely handled in Swing. This leads to NPE and
>>> InternalError as the code tries to access the data that has become
>>> unavailable.
>>> The fix:
>>> Windows desktop properties are updated right on Windows Toolkit thread,
>>> and the value of "win.xpstyle.themeActive" is stored in
>>> ThemeReader.xpStyleEnabled field. PropertyChangeEvents for desktop
>>> properties are delivered either synchronously on EDT or asynchronously
>>> via DesktopPropertyChangeSupport, as it used to be.
>>> Getters in XPStyle class check for null values and return dummy defaults
>>> if ThemeReader returned null. SkinPainters also check whether theming is
>>> still available before asking ThemeReader to paint.
>>> Access to XPStyle.xp instance is blocked as soon as user switches
>>> themes. The object will be cleaned when the corresponding
>>> PropertyChangeEvent is handled by Swing.
>>> This new version of the fix addresses issues found with the initial
>>> submission of JDK-8039383 fix:
>>>    - JDK-8046239: Build failure in 9-client on all non-Windows platforms
>>>    - JDK-8046391: Hang displaying JFileChooser with Windows L&F
>>> See also
>>> http://mail.openjdk.java.net/pipermail/awt-dev/2014-June/007975.html
>>> and http://cr.openjdk.java.net/~aivanov/8039383/jdk9/webrev.03/
>>> Regression test:
>>> No regression test is provided due to its complexity. Whether
>>> NullPointerException or InternalError are thrown depends on the order of
>>> event handling, sometimes exceptions do not occur when changing theme of
>>> visual styles enabled theme to a classic theme.
>>> I included regression test for hang in JFileChooser, JDK-8046391.
>>> Thank you,
>>> Alexey.

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