Bug 65444 [R21PRES] Close button shown when views not closeable
RC1 build - run the browser example using the R2.1 presentation - the views have close buttons in the titlebar, but should not because the perspective has fixed="true" (meaning that all initial views are non-moveable and non-closeable)
bundles/org.eclipse.ui.presentations.r21/src/org/eclipse/ui/internal/presentations/R21BasicStackPresentation.java
Window window = getWindow();
        if (window instanceof WorkbenchWindow)
            return ((WorkbenchWindow) window).getShellActivated();
        else
            return false;
    }
    /**
     * Returns the top level window.
     */
    public Window getWindow() {
        Control ctrl = getControl();
        if (ctrl != null) {
            Object data = ctrl.getShell().getData();
            if (data instanceof Window) return (Window) data;
        }
        return null;
    }
	
	private CTabItem createPartTab(IPresentablePart part, int tabIndex) {
		CTabItem tabItem;
		int style = SWT.NONE;
		
		if (getSite().isCloseable(part)) {
			style |= SWT.CLOSE;
		}
		
		tabItem = paneFolder.createItem(style, tabIndex);
				
		tabItem.setData(TAB_DATA, part);