At any time, one frame in XEmacs is the selected frame. The selected window always resides on the selected frame. As the focus moves from device to device, the selected frame on each device is remembered and restored when the focus moves back to that device.
nil is returned.
The X server normally directs keyboard input to the X window that the mouse is in. Some window managers use mouse clicks or keyboard events to shift the focus to various X windows, overriding the normal behavior of the server.
Lisp programs can switch frames "temporarily" by calling
the function select-frame. This does not override the window
manager; rather, it escapes from the window manager's control until
that control is somehow reasserted.
When using a text-only terminal, there is no window manager; therefore,
select-frame is the only way to switch frames, and the effect
lasts until overridden by a subsequent call to select-frame.
Only the selected terminal frame is actually displayed on the terminal.
Each terminal screen except for the initial one has a number, and the
number of the selected frame appears in the mode line after the word
`Emacs' (see section Variables Used in the Modeline).
Note that this does not actually cause the window-system focus to be set
to this frame, or the select-frame-hook or
deselect-frame-hook to be run, until the next time that XEmacs is
waiting for an event.