This is a quick one. The focused window border is sometimes unnecessary, particularly when using Full or Tabbed layouts, since only one window is visible. XMonad.Layout.NoBorders was built to fix this.
The simplest option is the noBorders modifier, which will simply never show the border on the layouts it is applied to. It is typically applied thus:
layoutHook = ... ||| noBorders Full ||| ... ||| noBorders Tabbed ||| ...
Using it on a layout that shows multiple windows, such as Tall, would be a bad idea. But what about Tall with only one window? There is also the smartBorders modifier that will hide the borders under either of two conditions:
- There is only one screen and only one window. (Note that on a Xinerama setup, this will never be true.)
- A floating window covers the entire screen (great for mplayer, probably the largest use case)
Since smartBorders handles all layouts, even those that can have multiple windows, it is best applied to your whole layoutHook:
layoutHook = avoidStruts $ ... $ smartBorders $ ... ||| tiled ||| ...
Adding to core
It has been argued that SmartBorders should be in core, and even be the default behaviour. The main argument against this is that it could be confusing, and that it is rather straightforward to set up. For now, setting up smartBorders is easy, and improves the fullscreen video experience.