Bug 305004 The PathVariableSelectionDialog should not use 'Extend' to build path variable arguments
The PathVariableSelectionDialog should not use 'Extend' to build path variable arguments, since this is used already to build a path, which could be used to build a path starting off an argumented path variable.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/dialogs/PathVariableSelectionDialog.java
* @see org.eclipse.swt.widgets.Listener#handleEvent(org.eclipse.swt.widgets.Event)
                     */
                    public void handleEvent(Event event) {
                        updateExtendButtonState();
                    }
                });
        setShellStyle(getShellStyle() | SWT.SHEET);
    }
    /* (non-Javadoc)
     * @see org.eclipse.jface.dialogs.Dialog#buttonPressed(int)
     */
    protected void buttonPressed(int buttonId) {
        if (buttonId == EXTEND_ID) {
            PathVariablesGroup.PathVariableElement selection = pathVariablesGroup
                    .getSelection()[0];
			IPathVariable pathVariable = null;
			if (currentResource != null)
				pathVariable = currentResource.getPathVariableManager().getPathVariable(selection.name);
			if (pathVariable != null
					&& pathVariable.getExtensions() != null) {
				EnvSelectionDialog dialog = new EnvSelectionDialog(getShell(),
						pathVariable.getExtensions());
            dialog.setTitle(IDEWorkbenchMessages.PathVariableSelectionDialog_ExtensionDialog_title);
            dialog.setMessage(NLS.bind(IDEWorkbenchMessages.PathVariableSelectionDialog_ExtensionDialog_description, selection.name));
				if (dialog.open() == Window.OK
						&& pathVariablesGroup.performOk()) {
					setSelectionResult(new String[] { "${" + selection.name + "-" + dialog.getResult()[0] + "}" }); 
					super.okPressed();
				}
			} else {