Bug 31556 Export jar from Navigator view fails
(M5 build) In Navigator view (resource perspective), right-click on a src/ directory containing your sources, select export->jar file and the package selector opens with no resource selected (and finish button disabled); but it seems that the src/ dir is really selected, because if you re-select it in the window, it ends up with a "jar creation failed" and a lot of duplicate entries in the error log. If you try the same from the Projects view (Java browsing perspective), it works fine.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/jarpackager/JarPackageWizardPage.java
GridData data= new GridData(GridData.HORIZONTAL_ALIGN_FILL | GridData.GRAB_HORIZONTAL);
		data.widthHint= SIZING_TEXT_FIELD_WIDTH;
		fDestinationNamesCombo.setLayoutData(data);
		
		fDestinationBrowseButton= new Button(destinationSelectionGroup, SWT.PUSH);
		fDestinationBrowseButton.setText(JarPackagerMessages.getString("JarPackageWizardPage.browseButton.text")); 
		fDestinationBrowseButton.setLayoutData(new GridData(GridData.HORIZONTAL_ALIGN_FILL));
		SWTUtil.setButtonDimensionHint(fDestinationBrowseButton);
		fDestinationBrowseButton.addSelectionListener(new SelectionAdapter() {
			public void widgetSelected(SelectionEvent e) {
				handleDestinationBrowseButtonPressed();
			}
		});
	}
	/**
	 *	Open an appropriate destination browser so that the user can specify a source
	 *	to import from
	 */
	protected void handleDescriptionFileBrowseButtonPressed() {
		SaveAsDialog dialog= new SaveAsDialog(getContainer().getShell());
		dialog.create();
		dialog.getShell().setText(JarPackagerMessages.getString("JarPackageWizardPage.saveAsDialog.title")); 
		dialog.setMessage(JarPackagerMessages.getString("JarPackageWizardPage.saveAsDialog.message")); 
		dialog.setOriginalFile(createFileHandle(fJarPackage.getDescriptionLocation()));
		if (dialog.open() == SaveAsDialog.OK) {
			IPath path= dialog.getResult();
			path= path.removeFileExtension().addFileExtension(JarPackagerUtil.DESCRIPTION_EXTENSION);
			fDescriptionFileText.setText(path.toString());
		}
	}