properties panel is now horizontal???

Not sure how this happened but all the sections of the properties panel are now lined up horizontally instead of vertically - so no I need to scroll way right (or left) to see all the sections instead of scrolling up or down. I suspect I hit some key combination to do this and looked at the user settings but unable to find anything related to this. Very odd. Any help would be great.

Right click anywhere in properties panels to set vertical or horizontal.

Edit: Well, any open space in a panel (not over a setting).

-LP

Thank you!!! Never considered the RMB. Feels like I just removed a pair of shoes that are too small.