<AWT Dev> [7u6] Review request for 7159266: [macosx] ApplicationDelegate should not be set in the headless mode

steve.x.northover at oracle.com steve.x.northover at oracle.com
Thu Apr 5 13:11:13 PDT 2012

Hi all,

Headless mode works fine for SWT.  SWT doesn't use eAWT to do Quit etc.  
Instead, it uses the appropriate native cocoa calls.


On 05/04/2012 11:23 AM, Anthony Petrov wrote:
> On 04/05/12 19:07, Mike Swingler wrote:
>>> Please review a fix for 
>>> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7159266 at:
>>> http://cr.openjdk.java.net/~anthony/7u6-4-fxHang-7159266.0/
>>> With this fix we avoid setting an application delegate when AWT is 
>>> started in the headless mode. This prevents a hang when another GUI 
>>> toolkit (e.g. JavaFX) is already running in the same Java process.
>> This would logically mean that you won't get eAWT events (file open, 
>> quit, etc) while started in this mode. Does this impact SWT as well?
> In the headless mode an application doesn't have any UI, and as such 
> there's no way to generate e.g. a Quit action. Hence the application 
> delegate isn't necessary in this mode.
> SWT uses a special "SWT mode" (== -XstartOnFirstThread) which is 
> different from the headless mode. In the SWT mode the delegate will 
> still be installed.
> I think this may not work in case of running an SWT application 
> together with the AWT in headless mode. However, I can't imagine who 
> might want to run SWT/AWT in such configuration because the headless 
> mode is supposed to be primarily used in server environments where a 
> display is physically unavailable, in which case SWT wouldn't be able 
> to run there either.
> -- 
> best regards,
> Anthony

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