Tile Horizonally / Tile Vertically
If your Xnews-windows aren't maximized here you make them display horizontally resp. vertically aligned.

Cascade
Non-maximized windows are displayed in an overlapping manner.

Arrange All
No visible effect on my system.

Open Folders
Opens on overview of all available folders. This includes the Sent-folder, the Outbox and the folders you created yourself.

Show Tabs
Shows/hides the buttons at the bottom of the screen which represent a single window (e.g. the servers group-list, the articles-list of a group, ...)

Minimize To Tray
Makes Xnews disappear from the desktop and the taskbar. What is left is a small icon in the system tray. Click on it to revive the program.

#.. [your opened windows]
The actually opened windows. For those who deactivated "Show Tabs" an alternative way to switch from window to window.