Each time I click away from an image or element within a design I'm working on, the left menu closes and the design shifts to the left. Then, when I click on an element in my design again, the menu opens and shifts my entire design over to the right, but not far enough to stop the left menu from blocking the element I'm working on. With long carousel-style designs especially, I end up having my design constantly shift back and forth throughout the design process. It gets really aggravating and imedes my work -- especially when this collapsing and expanding menu keeps blocking things. For the sake (and sanity) of the user, consider just leaving that menu open all the time.