IBM's OS/2 has a great history as a workstation operating system, it was a major alternative OS in the '90s. At its peak time in the mid-'90s OS/2 had about 2 million users but the Windows NT and Windows 95 releases broke its further development. This year
Serenity Systems has released a new client version of OS/2. This article will introduce you to what OS/2 is all about. You will learn its history, its user interface, and its power under the hood. The article is also accompanied by a number of screenshots.
"because it utilizes this weird widget, the arrow inside the rectangle"
OS/2 is the only operating system that I know of to get this right. It has two submenu widgets; one for when you can select the root menu item (that's the arrow with the box), and one for when you can't (just an arrow). All other OSes I know of force the user to decide if he/she can choose the root item based solely on context.