Function: redirect-frame-focus

redirect-frame-focus is a function defined in frame.c.

Signature

(redirect-frame-focus FRAME FOCUS-FRAME)

Documentation

Arrange for keystrokes typed at FRAME to be sent to FOCUS-FRAME.

In other words, switch-frame events caused by events in FRAME will request a switch to FOCUS-FRAME, and last-event-frame will be FOCUS-FRAME after reading an event typed at FRAME.

If FOCUS-FRAME is nil, any existing redirection is canceled, and the frame again receives its own keystrokes.

Focus redirection is useful for temporarily redirecting keystrokes to a surrogate minibuffer frame when a frame doesn't have its own minibuffer window.

A frame's focus redirection can be changed by select-frame. If frame FOO is selected, and then a different frame BAR is selected, any frames redirecting their focus to FOO are shifted to redirect their focus to BAR. This allows focus redirection to work properly when the user switches from one frame to another using select-window.

This means that a frame whose focus is redirected to itself is treated differently from a frame whose focus is redirected to nil; the former is affected by select-frame, while the latter is not.

The redirection lasts until redirect-frame-focus is called to change it.

View in manual

Source Code

// Defined in /usr/src/emacs/src/frame.c
{
  /* Note that we don't check for a live frame here.  It's reasonable
     to redirect the focus of a frame you're about to delete, if you
     know what other frame should receive those keystrokes.  */
  struct frame *f = decode_any_frame (frame);

  if (! NILP (focus_frame))
    CHECK_LIVE_FRAME (focus_frame);

  fset_focus_frame (f, focus_frame);

  if (FRAME_TERMINAL (f)->frame_rehighlight_hook)
    (*FRAME_TERMINAL (f)->frame_rehighlight_hook) (f);

  return Qnil;
}