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How can a widget be disposed without a call to dispose()? [message #870858]

Thu, 10 May 2012 01:59

Eric Rizzo

Messages: 3071
Registered: July 2009

Senior Member

How is it possible for a widget to be disposed if its dispose() was never called? I'm seeing an odd bug in an RCP app that shows up as:

org.eclipse.swt.SWTException: Widget is disposed

So I set a breakpoint in

Widget.dispose()

to find out how/why it was being disposed. To my surprise, the breakpoint was never hit for the widget in question.

Here's the top of the stack trace:

org.eclipse.swt.SWTException: Widget is disposed
	at org.eclipse.swt.SWT.error(SWT.java:4282)
	at org.eclipse.swt.SWT.error(SWT.java:4197)
	at org.eclipse.swt.SWT.error(SWT.java:4168)
	at org.eclipse.swt.widgets.Widget.error(Widget.java:774)
	at org.eclipse.swt.widgets.Widget.checkWidget(Widget.java:568)
	at org.eclipse.swt.widgets.Widget.addDisposeListener(Widget.java:467)
	at org.eclipse.jface.fieldassist.ControlDecoration.addControlListeners(ControlDecoration.java:602)
	at org.eclipse.jface.fieldassist.ControlDecoration.<init>(ControlDecoration.java:476)
	at org.eclipse.jface.fieldassist.ControlDecoration.<init>(ControlDecoration.java:428)

This is an RCP app built against a 3.7.2 target platform.

[Updated on: Thu, 10 May 2012 02:02]

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Re: How can a widget be disposed without a call to dispose()? [message #871088 is a reply to message #870858]

Thu, 10 May 2012 18:51

Paul Webster

Messages: 6859
Registered: July 2009
Location: Ottawa

Senior Member

You'd have to add a dispose listener to the widget when it's created to find out when it is disposed. In SWT, if I dispose a Composite, it disposes all of its children. Their dispose isn't called, but they would get SWT.Dispose events.

PW

Paul Webster
http://wiki.eclipse.org/Platform_Command_Framework
http://wiki.eclipse.org/Command_Core_Expressions
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Re: How can a widget be disposed without a call to dispose()? [message #871098 is a reply to message #871088]

Thu, 10 May 2012 20:20

Eric Rizzo

Messages: 3071
Registered: July 2009

Senior Member

Thanks, Paul. I didn't know widgets would be disposed that way without their dispose() being called. I'll set up a dispose listener to see if I can find what's happening.

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