Avoid using the "no window manager" code in Emacs

* exwm.el (exwm--on-ClientMessage): Handle fullscreen requests
	for frames.
	(exwm-init): Initialize workspaces after unlocking events.

	* exwm-workspace.el (exwm-workspace--init): Create frames as
	invisible, then make them visible only once their OverrideRedirect
	property has been set.

	* exwm-randr.el (exwm-randr--refresh): New frame parameter
	`exwm-geometry'.

	* exwm-layout.el (exwm-layout--set-frame-fullscreen): New
        function.

The Emacs code is buggy, see https://github.com/ch11ng/exwm/issues/39

https://github.com/ch11ng/exwm/pull/42

exwm-layout.el

@@ -162,6 +162,34 @@
     (setq exwm--fullscreen nil)
     (exwm-input-grab-keyboard)))
 
+;; This function is superficially similar to `exwm-layout-set-fullscreen', but
+;; they do very different things: `exwm-layout--set-frame-fullscreen' resizes a
+;; frame to the actual monitor size, `exwm-layout-set-fullscreen' resizes an X
+;; window to the frame size.
+(defun exwm-layout--set-frame-fullscreen (frame)
+  "Make frame FRAME fullscreen, with regard to its XRandR output if applicable."
+  (let ((geometry (or (frame-parameter frame 'exwm-geometry)
+                      (xcb:+request-unchecked+reply
+                          exwm--connection
+                          (make-instance 'xcb:GetGeometry
+                                         :drawable exwm--root))
+                      (make-instance 'xcb:RECTANGLE :x 0 :y 0
+                                     :width (x-display-width)
+                                     :height (x-display-height))))
+         (id (frame-parameter frame 'exwm-outer-id)))
+    (with-slots (x y width height) geometry
+                (xcb:+request exwm--connection
+                    (make-instance 'xcb:ConfigureWindow
+                                   :window id
+                                   :value-mask (logior xcb:ConfigWindow:X
+                                                       xcb:ConfigWindow:Y
+                                                       xcb:ConfigWindow:Width
+                                                       xcb:ConfigWindow:Height)
+                                   :x x :y y
+                                   :width width
+                                   :height height))
+                (xcb:flush exwm--connection))))
+
 (defun exwm-layout--refresh ()
   "Refresh layout."
   (let ((frame (selected-frame))

exwm-randr.el

@@ -85,6 +85,12 @@
           (setq geometry default-geometry
                 output nil))
         (set-frame-parameter frame 'exwm-randr-output output)
+        (set-frame-parameter frame 'exwm-geometry
+                             (make-instance 'xcb:RECTANGLE
+                                            :x (elt geometry 0)
+                                            :y (elt geometry 1)
+                                            :width (elt geometry 2)
+                                            :height (elt geometry 3)))
         (set-frame-parameter frame 'exwm-x (elt geometry 0))
         (set-frame-parameter frame 'exwm-y (elt geometry 1))
         (xcb:+request exwm--connection

exwm-workspace.el

@@ -231,13 +231,11 @@ The optional FORCE option is for internal use only."
       (unless (frame-parameter i 'window-id)
         (setq exwm-workspace--list (delq i exwm-workspace--list)))))
   (cl-assert (= 1 (length exwm-workspace--list)))
-  (exwm--make-emacs-idle-for 0.1)      ;wait for the frame ready
-  ;; Configure the existing frame
-  (set-frame-parameter (car exwm-workspace--list) 'fullscreen 'fullboth)
   ;; Create remaining frames
   (dotimes (i (1- exwm-workspace-number))
     (nconc exwm-workspace--list
-           (list (make-frame '((window-system . x) (fullscreen . fullboth))))))
+           (list (make-frame '((window-system . x)
+                               (visibility . nil))))))
   ;; Configure workspaces
   (dolist (i exwm-workspace--list)
     (let ((window-id (string-to-int (frame-parameter i 'window-id)))
@@ -256,6 +254,14 @@ The optional FORCE option is for internal use only."
                          :window window-id :value-mask xcb:CW:EventMask
                          :event-mask xcb:EventMask:SubstructureRedirect))))
   (xcb:flush exwm--connection)
+  ;; We have to delay making the frame visible until the
+  ;; override-redirect flag has been set.
+  (select-frame-set-input-focus (car exwm-workspace--list))
+  (dolist (i exwm-workspace--list)
+    (set-frame-parameter i 'visibility t)
+    (lower-frame i)
+    (set-frame-parameter i 'fullscreen 'fullboth))
+  (raise-frame (car exwm-workspace--list))
   ;; Handle unexpected frame switch
   (add-hook 'focus-in-hook 'exwm-workspace--on-focus-in)
   ;; Switch to the first workspace

exwm.el

@@ -441,6 +441,20 @@
             (props (list (elt data 1) (elt data 2)))
             (buffer (exwm--id->buffer id))
             props-new)
+        ;; only support _NET_WM_STATE_FULLSCREEN / _NET_WM_STATE_ADD for frames
+        (when (and (not buffer)
+                   (memq xcb:Atom:_NET_WM_STATE_FULLSCREEN props)
+                   (= action xcb:ewmh:_NET_WM_STATE_ADD))
+          (dolist (f exwm-workspace--list)
+            (when (equal (frame-parameter f 'exwm-outer-id) id)
+	      (exwm-layout--set-frame-fullscreen f)
+	      (xcb:+request
+                  exwm--connection
+                  (make-instance 'xcb:ewmh:set-_NET_WM_STATE
+                                 :window id
+                                 :data (vector
+                                        xcb:Atom:_NET_WM_STATE_FULLSCREEN)))
+	      (xcb:flush exwm--connection))))
         (when buffer                    ;ensure it's managed
           (with-current-buffer buffer
             ;; _NET_WM_STATE_MODAL
@@ -609,14 +623,14 @@
         ;; (xcb:icccm:init exwm--connection)
         (xcb:ewmh:init exwm--connection)
         (exwm--lock)
-        (exwm-workspace--init)
         (exwm--init-icccm-ewmh)
         (exwm-layout--init)
         (exwm-floating--init)
         (exwm-manage--init)
         (exwm-input--init)
         (exwm--unlock)
-        ;; Manage exiting windows
+        (exwm-workspace--init)
+        ;; Manage existing windows
         (exwm-manage--scan)
         (run-hooks 'exwm-init-hook)))))