Bug 332930 Simplify code from bug 207510
There is a listener added to ProjectPreferences that will never be removed. Try to simplify the code to get rid of this listener.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/dialogs/ResourceEncodingFieldEditor.java
shell = page.getShell();
			}
			MessageDialog dialog = new MessageDialog(
					shell,
					IDEWorkbenchMessages.ResourceEncodingFieldEditor_EncodingConflictTitle,
					null,
					NLS
							.bind(
									IDEWorkbenchMessages.ResourceEncodingFieldEditor_EncodingConflictMessage,
									encoding, descriptionCharset),
					MessageDialog.WARNING, new String[] {
							IDialogConstants.YES_LABEL,
							IDialogConstants.NO_LABEL }, 0) {
				protected int getShellStyle() {
					return super.getShellStyle() | SWT.SHEET;
				}
			}; 
			
			if (dialog.open() > 0) {
				return;
			}
		}
		IDEEncoding.addIDEEncoding(encoding);
		final String finalEncoding = encoding;
		Job charsetJob = new Job(IDEWorkbenchMessages.IDEEncoding_EncodingJob) {
			/*
			 * (non-Javadoc)
			 * 
			 * @see org.eclipse.core.runtime.jobs.Job#run(org.eclipse.core.runtime.IProgressMonitor)
			 */