Mac: It's pretty annoying to deal with a multi-columned window and not be able to resize it properly for a good view. There's a quick way to resize Finder columns in unison, and quickly expand or minimise the view.
Just press and hold Shift + Option then click a column and drag. When you drag to the right, the columns will expand. When you drag to the left, they will shrink. It's an easy way to get the full view of Finder or otherwise shrink down the columns to fit a smaller window space should you need to.