Improve input focus switch mechanism

This commit should fix most input focus bugs (especially those related to
floating windows). The actual settings of input focus are delayed to exclude
redundant event. Dead code since this commit is removed.

This commit also fixes a bug for non-floating windows converted form floating
state. The workaround for `ido-mode` is also improved to properly handle
`exwm-mode` buffers.

exwm-manage.el

@@ -183,15 +183,8 @@ corresponding buffer.")
         (let ((floating exwm--floating-frame))
           (kill-buffer)
           (when floating
-            (if (eq 'exwm-mode
-                    (with-current-buffer
-                        (window-buffer
-                         (frame-first-window exwm-workspace--current))
-                      major-mode))
-                ;; Input focus is to be set on a window
-                (x-focus-frame exwm-workspace--current)
-              ;; Set input focus on a frame
-              (select-frame-set-input-focus exwm-workspace--current))))))))
+            (select-window
+             (frame-selected-window exwm-workspace--current))))))))
 
 (defun exwm-manage--scan ()
   "Search for existing windows and try to manage them."