It was really well integrated, if the window was too close to the edge, the window would move as the drawer opened in a single smooth animation.
XCode in particular had drawers everywhere.
As iTunes became successful, and everything wanted to be brushed metal, drawers began to disappear in favour of columns.
It's quite hard on the modern internet to find images of that old UI, but here's Preview with its right-hand-side drawer: https://mac.elated.com/2007/05/09/displaying-images-in-the-r...