<AWT Dev> [8] Request for review: JDK-8016555: Regression: Focus issues with Oracle WebCenter Capture applet

Anton V. Tarasov anton.tarasov at oracle.com
Fri Jun 14 05:10:26 PDT 2013

It's Ok because the check actually should be correct for any type of toplevels.


On 14.06.2013 10:54, Leonid Romanov wrote:
> Hi,
> The check you've added also affects lightweight frames (because of line 382). Is it OK?
> On 6/13/2013 6:52 PM, Anton V. Tarasov wrote:
>> Hello,
>> Please, review the fix.
>> jira: https://jbs.oracle.com/bugs/browse/JDK-8016555
>> webrev: http://cr.openjdk.java.net/~ant/JDK-8014821/webrev.0
>> It's reproducible in the applet mode only, on Windows. When an applet is focused and then a new 
>> frame pops up, it doesn't get focus.
>> The reason of the focus loss is the following. When a toplevel is shown while another toplevel is 
>> focused, native focus messages should be generated strictly in the following order: 
>> WM_ACTIVATE(WA_INACTIVE), WM_ACTIVATE(WA_ACTIVE), appropriately. The case with applet is special 
>> due to the EmbeddedFrame is not a toplevel from native platform perspective, the toplevel is the 
>> browser window. Moreover, the EmbeddedFrame window belongs to another process, other than the 
>> browser's process. It doesn't receive WM_ACTIVATE messages, these messages are generated 
>> (synthesized) for it when it should be activated/deactivated as an AWT toplevel. When 
>> EmbeddedFrame loses focus it receives WM_KILLFOCUS (which is triggered by the plugin). However, 
>> in case when a new frame pops up, the EmbeddedFrame receives WM_KILLFOCUS after the frame 
>> receives WM_ACTIVATE(WA_ACTIVE). So the order is not correct. The reason is the specific of IPC: 
>> browser -> plugin -> applet (another process).
>> When EmbeddedFrame receives WM_KILLFOCUS it synthesizes WM_ACTIVATE(WA_INACTIVE) for itself. On 
>> processing of this message, AwtComponent::SetFocusedWindow() static method is called which resets 
>> the native pointer to the focused window. The point is that as the message is received after 
>> WM_ACTIVATE(WA_ACTIVE) (which is sent to the new frame), the new focused window is set to NULL. 
>> Later, when focus is requested to the frame's default component, it gets rejected because of the 
>> null native focused window value.
>> Before the regression, there was a check for opposite toplevel being set focused in processing of 
>> WM_KILLFOCUS for EmbeddedFrame. In case the opposite toplevel is already set focused (which means 
>> it already received WM_ACTIVATE(WA_ACTIVE)), no WM_ACTIVATE(WA_INACTIVE) message was synthesized. 
>> DKFM in that case created a peer WINDOW_LOST_FOCUS event on java level for the toplevel losing 
>> focus (EmbeddedFrame in our case). This code was lost in the process of refactoring and I'm 
>> simply bring it back.
>> I've tested it manually with the applet provided in the bugreport (with IE and FF).
>> As the fix simply makes the code spot look like it was before the regression, I consider it low 
>> risk.
>> Thanks,
>> Anton.
>> P.S.
>> I'm going to push it to 7u40 as well.

More information about the awt-dev mailing list