<AWT Dev> Code Review Request for CR 7128738 - dragged dialog freezes system on dispose

[Anthony Petrov]

Hi Oleg,

The test is good, although I suggest to insert manual delays (of 
500...1500 ms) between showing frames, clicking, calling dispose(), etc. 
Unfortunately, the waitForIdle() alone doesn't guarantee much when it 
comes to processing native events.

Also, the test doesn't belong to the DnD area since the issue isn't 
related to the AWT DnD API. The test should be in java/awt/Frame/ 
directory with the "toplevel" area.

But otherwise the changes look fine, so provided the above suggestions 
are applied, I'm approving the fix. Thanks!

--
best regards,
Anthony

On 3/15/2012 12:54 AM, Oleg Pekhovskiy wrote:
> Hi Anthony,
> 
> thanks you for your proposal!
> 
> Freezing behavior occurs only until JVM finishes, when all other java 
> objects are disposed.
> In example provided in CR's evaluation field the primary frame prevents 
> JVM from finishing, that causes freezing.
> 
> So, the test, I propose, disposes the primary frame, that eliminates 
> freezing:
> http://cr.openjdk.java.net/~bagiras/8/7128738.2
> 
> Thanks,
> Oleg
> 
> 3/14/2012 6:16 AM, Anthony Petrov wrote:
>> Hi Oleg,
>>
>> The fix looks good to me. It would be cool to write a regression test 
>> for the issue, btw. You could start dragging a frame using Robot, and 
>> then call dispose() a couple seconds before releasing a mouse button. 
>> The test would fail by time-out w/o the fix.
>>
>> -- 
>> best regards,
>> Anthony
>>
>> On 3/14/2012 1:54 AM, Oleg Pekhovskiy wrote:
>>> Hi guys,
>>>
>>> please review the fix for:
>>> http://bugs.sun.com/view_bug.do?bug_id=7128738
>>>
>>> webrev:
>>> http://cr.openjdk.java.net/~bagiras/7128738.1
>>>
>>> Description:
>>>
>>> Entering 'move window' mode clicking window title bar sends 
>>> WM_SYSCOMMAND with SC_MOVE inside WM_NCLBUTTONDOWN.
>>> As a result additional message pump (for mouse capture) is created 
>>> blocking the handlers' chain WM_NCLBUTTONDOWN -> WM_SYSCOMMAND.
>>>
>>> So when JFrame.dispose() is called during this situation, deleting of 
>>> native AwtFrame object could NOT be done because 
>>> AwtComponent::CanBeDeleted() returns FALSE
>>> (because of WM_NCLBUTTONDOWN & WM_SYSCOMMAND) and WM_AWT_DELETEOBJECT 
>>> message is reposted over and over again (eating CPU time).
>>>
>>> Thus I added ReleaseDragCapture(0) to AwtComponent::Dispose() to 
>>> release mouse capture and finish the additional message pump
>>> so that AwtComponent::CanBeDeleted() returns TRUE and AwtFrame object 
>>> is deleted.
>>>
>>> Thanks,
>>> Oleg
>