Fix input dispatch: custom event loop + modal menu support

The deadlock: frame_timer_cb called WMHandleEvent which entered
menuMouseDown's modal WMMaskEvent loop. That blocked inside
wl_event_loop_dispatch (reentrant), preventing new events.

Fix:
1. Replace wl_display_run() with custom loop that drains WINGs
   events BETWEEN wl_event_loop_dispatch calls (not inside timer)
2. Make WINGs wl_flush() pump wlroots (call dispatch_fn) so
   WMMaskEvent modal loops get new events without reentrancy
3. Fix wBalloonHide NULL dereference (scr->balloon not allocated)
4. Remove XEvent dependency from wSelectWindows (takes x,y now)
5. Remove debug traces

Right-click on background now opens the root menu.

WINGs/wevent_wl.c

@@ -150,7 +150,12 @@ wl_check_typed_window(void *ectx, WNativeWindow w, int type, WMEvent *ev)
 static void
 wl_flush(void *ectx, Bool discard)
 {
-    (void)ectx; (void)discard;
+    WLEventCtx *ctx = ectx;
+    (void)discard;
+    /* Pump the wlroots event loop so pointer/key events arrive in our queue.
+     * This is called from waitForEvent/WMMaskEvent when the queue is empty. */
+    if (ctx->dispatch_fn)
+        ctx->dispatch_fn(0, ctx->dispatch_ud);
 }
 
 static int

src/backend/wayland/wl_backend.c

@@ -194,12 +194,13 @@
 #include "../../icon.h"        /* WIcon, TILE_* */
 #include "../../appicon.h"     /* WAppIcon */
 #include "../../menu.h"        /* WMenu, WMenuEntry */
+#include "../../balloon.h"     /* WBalloon */
 #include "../backend.h"
 #include "wl_backend.h"
 
 /* ------------------------------------------------------------------ */
-/* WINGs event backend interface (declared in WINGs/WINGsP.h)          */
-/* Forward-declared here to avoid pulling the full private header.     */
+/* WINGs private header — needed for W_EventBackend, W_Screen fields */
+#include <WINGs/WINGsP.h>
 /* ------------------------------------------------------------------ */
 #include <WINGs/WMEvent.h>
 struct W_Screen;
@@ -364,6 +365,7 @@ struct wl_compositor_state {
     struct wl_event_source         *x11_event_source; /* wl_event_loop fd watcher for x_display */
     pthread_t                       startup_pump_thread;  /* pumps Wayland event loop during StartUp() */
     volatile int                    startup_pump_running; /* 1 while pump thread is active */
+    volatile int                    terminate;           /* set to exit main loop */
     /* Phase 20: real input devices from nested backend + their listeners */
     struct wlr_input_device        *real_keyboard_dev;
     struct wlr_input_device        *real_pointer_dev;
@@ -545,8 +547,7 @@ wl_shutdown_pipe_handler(int fd, uint32_t mask, void *data)
     /* drain the pipe so the fd does not stay readable */
     while (read(fd, buf, sizeof(buf)) > 0)
         ;
-    if (wl_state.display)
-        wl_display_terminate(wl_state.display);
+    wl_state.terminate = 1;
     return 0;
 }
 
@@ -554,13 +555,12 @@ static int
 frame_timer_cb(void *data)
 {
     (void)data;
-    /* Skip wlroots rendering calls while the startup pump thread is running —
-     * wlr_output_send_frame involves EGL context operations that are not safe
-     * to call from a non-main thread. */
+
     if (!wl_state.startup_pump_running) {
         if (!wl_state.is_nested && wl_state.output)
             wlr_output_send_frame(wl_state.output);
     }
+
     if (wl_state.frame_timer)
         wl_event_source_timer_update(wl_state.frame_timer, 16);
     return 0;
@@ -2797,9 +2797,8 @@ wl_signalfd_handler(int fd, uint32_t mask, void *data)
     /* Set the exit state flag so post-loop cleanup paths see it. */
     SIG_WCHANGE_STATE(WSTATE_NEED_EXIT);
 
-    /* Terminate the event loop from within loop context. */
-    if (wl_state.display)
-        wl_display_terminate(wl_state.display);
+    /* Terminate the event loop. */
+    wl_state.terminate = 1;
 
     return 0;
 }
@@ -2919,7 +2918,33 @@ wl_event_loop_run(void)
     }
 
     wwarning("wl_backend: event loop running");
-    wl_display_run(wl_state.display);
+
+    /* Custom event loop: pump wlroots, then drain WINGs events.
+     * We can't use wl_display_run() because WM event handlers (OpenRootMenu,
+     * etc.) call WMMaskEvent which re-enters the wlroots loop.  By draining
+     * WINGs events BETWEEN dispatches (not inside a timer callback), modal
+     * loops in WMMaskEvent can safely call wl_event_loop_dispatch. */
+    {
+        struct wl_event_loop *loop = wl_display_get_event_loop(wl_state.display);
+        while (!wl_state.terminate) {
+            wl_display_flush_clients(wl_state.display);
+            wl_event_loop_dispatch(loop, 16);
+
+            /* Drain WINGs event queue */
+            WMScreen *wmscr = wl_get_wmscreen();
+            if (wmscr) {
+                const W_EventBackend *be = wmscr->eventBackend;
+                void *ectx = wmscr->eventBackendCtx;
+                WMEvent wev;
+                int limit = 64;
+                while (be->pending(ectx) && limit-- > 0) {
+                    be->fetch(ectx, &wev);
+                    WMHandleEvent(&wev);
+                }
+            }
+        }
+    }
+
     wwarning("wl_backend: event loop exited");
 }
 
@@ -6414,7 +6439,10 @@ static void wl_noop_icon_select(WIcon *icon) { (void)icon; }
 static void wl_noop_icon_change_title(WIcon *icon, WWindow *wwin) { (void)icon; (void)wwin; }
 static void wl_clip_icon_paint(WAppIcon *aicon) { wl_appicon_paint(aicon); }
 static void wl_drawer_icon_paint(WAppIcon *aicon) { wl_appicon_paint(aicon); }
-static void wl_noop_balloon_init(WScreen *scr) { (void)scr; }
+static void wl_balloon_init(WScreen *scr)
+{
+    scr->balloon = wmalloc(sizeof(WBalloon));
+}
 static void wl_noop_do_kaboom(WScreen *scr, WNativeWindow win, int x, int y)
 { (void)scr; (void)win; (void)x; (void)y; }
 static void wl_menu_paint_entry(WMenu *menu, int index, int selected)
@@ -6887,7 +6915,7 @@ const WMBackend wl_backend = {
     .icon_change_title      = wl_noop_icon_change_title,
     .clip_icon_paint        = wl_clip_icon_paint,
     .drawer_icon_paint      = wl_drawer_icon_paint,
-    .balloon_init           = wl_noop_balloon_init,
+    .balloon_init           = wl_balloon_init,
     .do_kaboom              = wl_noop_do_kaboom,
     .menu_paint_entry       = wl_menu_paint_entry,
     .menu_draw_frame        = wl_menu_draw_frame,

src/balloon.c

@@ -262,7 +262,7 @@ void wBalloonEnteredObject(WScreen *scr, WObjDescriptor *object)
 
 void wBalloonHide(WScreen *scr)
 {
-	if (scr) {
+	if (scr && scr->balloon) {
 		if (scr->balloon->mapped) {
 			wm_backend->window_unmap((WNativeWindow)scr->balloon->window);
 			scr->balloon->mapped = 0;

src/event.c

@@ -149,6 +149,7 @@ static void wdelete_death_handler(WMagicNumber id)
 
 void DispatchEvent(WMEvent * event)
 {
+
 	if (deathHandlers)
 		handleDeadProcess();
 

src/startup.c

@@ -379,11 +379,9 @@ void StartUp(Bool defaultScreenOnly)
 	/* handle X shutdowns and errors via backend */
 	wm_backend->register_error_handlers();
 
-	/* set hook for our event dispatcher in WINGs event dispatcher (X11 only).
-	 * Skip for Wayland: we run a wlroots event loop, not a WINGs/X11 loop.
-	 * dpy may be set (XWayland bridge), but X11 event dispatch is not used. */
-	if (!wm_backend->is_wayland)
-		WMHookEventHandler(DispatchEvent);
+	/* set hook for our event dispatcher in WINGs event dispatcher.
+	 * In Wayland mode, events are drained from the frame timer. */
+	WMHookEventHandler(DispatchEvent);
 
 	/* initialize defaults stuff */
 	w_global.domain.wmaker = wDefaultsInitDomain("WindowMaker", True);