Add/improve some ICCCM/EWMH features

* exwm-floating.el (exwm-floating--set-allowed-actions)
(exwm-floating--set-floating, exwm-floating--unset-floating):
Add _NET_WM_ALLOWED_ACTIONS support.

* exwm-floating.el (exwm-floating--set-floating)
(exwm-floating--unset-floating): Support initial state hint.
* exwm.el (exwm--update-hints): Fetch initial state.
(exwm--update-state, exwm--on-PropertyNotify):
WM_STATE is not intended to be read.
* exwm-core.el (exwm-state):
* exwm-floating.el (exwm-floating-hide):
* exwm-input.el (exwm-input--update-focus):
* exwm-layout.el (exwm-layout--set-state)
(exwm-layout--iconic-state-p, exwm-layout--show, exwm-layout--hide):
* exwm-manage.el (exwm-manage--on-MapRequest):
Improve WM_STATE support.

* exwm-input.el (exwm-input--set-focus):
* exwm-input.el (exwm-input--update-focus)
(exwm-input--set-active-window):
* exwm.el (exwm--on-ClientMessage): Add _NET_ACTIVE_WINDOW support.

* exwm-layout.el (exwm-layout--set-client-list-stacking):
Improve _NET_CLIENT_LIST_STACKING support.

* exwm-manage.el (exwm-manage--set-client-list)
(exwm-manage--manage-window, exwm-manage--unmanage-window):
Improve _NET_CLIENT_LIST support.

* exwm-manage.el (exwm-manage--manage-window):
* exwm-workspace.el (exwm-workspace--set-desktop)
(exwm-workspace-move-window):
* exwm.el (exwm--on-ClientMessage): Add _NET_WM_DESKTOP support.

* exwm-randr.el (exwm-randr--refresh):
* exwm-workspace.el (exwm-workspace--set-desktop-geometry)
(exwm-workspace--init): Add _NET_DESKTOP_GEOMETRY support.

* exwm-workspace.el (exwm-workspace--set-desktop-geometry):
Renamed from `exwm-workspace--update-desktop-geometry'.
* exwm-randr.el (exwm-randr--refresh): Improve _NET_WORKAREA support.

* exwm-workspace.el (exwm-workspace--set-fullscreen):
Correct variables names.

* exwm-workspace.el (exwm-workspace--init):
* exwm.el (exwm--init-icccm-ewmh):
Set _NET_NUMBER_OF_DESKTOPS in workspace module.

* exwm-workspace.el (exwm-workspace--init):
* exwm.el (exwm--init-icccm-ewmh):
Set _NET_DESKTOP_VIEWPORT in workspace module.

* exwm.el (exwm--on-ClientMessage): Improve _NET_CURRENT_DESKTOP
support.

* exwm.el (exwm--on-ClientMessage): Add _NET_CLOSE_WINDOW support.

* exwm.el (exwm--on-ClientMessage): Add WM_CHANGE_STATE support.

* exwm.el (exwm--init-icccm-ewmh): Update supported atoms.

exwm-input.el

@@ -76,6 +76,7 @@ It's updated in several occasions, and only used by `exwm-input--set-focus'.")
                            :revert-to xcb:InputFocus:PointerRoot
                            :focus id
                            :time xcb:Time:CurrentTime)))
+      (exwm-input--set-active-window id)
       (xcb:flush exwm--connection))))
 
 (defvar exwm-input--focus-window nil "The (Emacs) window to be focused.")
@@ -99,6 +100,9 @@ It's updated in several occasions, and only used by `exwm-input--set-focus'.")
 (defvar exwm-workspace-current-index)
 (defvar exwm-workspace--minibuffer)
 
+(declare-function exwm-layout--iconic-state-p "exwm-layout.el" (&optional id))
+(declare-function exwm-layout--set-state "exwm-layout.el" (id state))
+
 (defun exwm-input--update-focus ()
   "Update input focus."
   (when (and (window-live-p exwm-input--focus-window)
@@ -136,13 +140,26 @@ It's updated in several occasions, and only used by `exwm-input--set-focus'.")
                                    :window exwm--container
                                    :value-mask xcb:ConfigWindow:StackMode
                                    :stack-mode xcb:StackMode:Above)))
+              ;; This floating X window might be hide by `exwm-floating-hide'.
+              (when (exwm-layout--iconic-state-p)
+                (exwm-layout--set-state exwm--id
+                                        xcb:icccm:WM_STATE:NormalState))
               (xcb:flush exwm--connection)))
         (when (eq (selected-window) exwm-input--focus-window)
           (exwm--log "Focus on %s" exwm-input--focus-window)
           (select-frame-set-input-focus (window-frame exwm-input--focus-window)
-                                        t)))
+                                        t)
+          (exwm-input--set-active-window)
+          (xcb:flush exwm--connection)))
       (setq exwm-input--focus-window nil))))
 
+(defun exwm-input--set-active-window (&optional id)
+  "Set _NET_ACTIVE_WINDOW."
+  (xcb:+request exwm--connection
+      (make-instance 'xcb:ewmh:set-_NET_ACTIVE_WINDOW
+                     :window exwm--root
+                     :data (or id xcb:Window:None))))
+
 (defvar exwm-input--during-key-sequence nil
   "Non-nil indicates Emacs is waiting for more keys to form a key sequence.")
 (defvar exwm-input--temp-line-mode nil