A focus policy. The window manager gives the keyboard focus to the last window the mouse pointer was in. It feels like a cross between click to focus (the focus is reasonably "sticky") and point to focus (no "explicit" action needs to be taken to transfer focus).

This is increasingly common in the X world (it exists at least in KDE's kwm, in fvwm2, and in wmx); to my knowledge, it does not exist in Windows in any form.

The most common way to transfer focus when using sloppy focus is to push the mouse through the window

Annoyances:

  • Accidental mouse jogging is still a problem, though a much smaller one than with point to focus.
  • May still need to click to focus on a particular text field of the window.