I have my categories so, that when you click on them you get into category-view. Meaning I do have "Create Pages for Categories" enabled. when you are viewing a specific category-page, then you click onto the small icon for "open quick navigation". then it shows (for about half a second) only the blank background-color of my website, before the "quick navigation menu" is opening up. Not sure whether is is some delay until the white-transparent overlay and the quick navigation opens. But it does not look great when seeing just the background-color for half a second...... This strange effect does not happen when clicking on the "quick navigation menu" at the homepage (Forum List). It only happens when viewing the categories (category-pages).