I'm not sure if this is intentional or a browser bug (I'm using Chrome so anything Webkit/Safari should be the same) but at the bottom of the menu panel on the

I'm not sure if this is intentional or a browser bug (I'm using Chrome so anything Webkit/Safari should be the same) but at the bottom of the menu panel on the left I see a resize button (bottom right of left panel). If I resize the panel, the menu itself doesn't resize, only the right side menus shrink.