Bug 53327 [Progress] Second manual build should optionally cancel the first
M7 If you select a Rebuild All from the workbench this is now run in the background. If it is run again then the user should be prompted to cancel either the new one or the one running. We should also have a "don't ask me again" option.
bundles/org.eclipse.ui.ide/extensions/org/eclipse/ui/actions/GlobalBuildAction.java
if (roots[i].isAccessible())
				if (roots[i].getDescription().getBuildSpec().length > 0)
					return true;
		}
	}
	catch (CoreException e) {
		IDEWorkbenchPlugin.log("Exception in " + getClass().getName() + ".run: " + e);
		ErrorDialog.openError(
			getShell(),
			IDEWorkbenchMessages.getString("GlobalBuildAction.buildProblems"), 
			IDEWorkbenchMessages.format("GlobalBuildAction.internalError", new Object[] {e.getMessage()}), 
			e.getStatus());
		return false;
	}
	
	return false;
}
/* (non-Javadoc)
 * Method declared on ActionFactory.IWorkbenchAction.
 * @since 3.0
 */
public void dispose() {
	if (workbenchWindow == null) {
		
		return;
	}
	workbenchWindow = null;
}
}