Bug 273489 [Mac] We should not nest sheets
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/dialogs/PathVariableDialog.java
public void modifyText(ModifyEvent event) {
                variableValueModified();
            }
        });
        
        Composite buttonsComposite = new Composite(contents, SWT.NONE);
        buttonsComposite.setLayoutData(new GridData(SWT.END, SWT.CENTER, false,
        		false));
        GridLayout layout = new GridLayout(2, true);
        layout.marginWidth = 0;
        layout.marginHeight = 0;
        buttonsComposite.setLayout(layout);
        
        fileButton = new Button(buttonsComposite, SWT.PUSH);
        fileButton.setText(IDEWorkbenchMessages.PathVariableDialog_file);
        fileButton.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, false,
        		false));
        if ((variableType & IResource.FILE) == 0) {
			fileButton.setEnabled(false);
		}
        fileButton.addSelectionListener(new SelectionAdapter() {
            public void widgetSelected(SelectionEvent e) {
                selectFile();
            }
        });
        
        folderButton = new Button(buttonsComposite, SWT.PUSH);
        folderButton.setText(IDEWorkbenchMessages.PathVariableDialog_folder);
        folderButton.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, false,
        		false));