Better handle devices being enabled on XI2

* src/xterm.c (handle_one_xevent): Don't abort on DeviceChanged
if the device couldn't be found, instead regenerating the device
hierarchy to see if it was enabled.

1 files changed, 17 insertions, 1 deletions

diff --git a/src/xterm.c b/src/xterm.c
index cff4b07c6ea..9c24a074e3d 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -581,6 +581,11 @@ x_free_xi_devices (struct x_display_info *dpyinfo)
 /* Setup valuator tracking for XI2 master devices on
    DPYINFO->display.  */
 
+/* This function's name is a misnomer: these days, it keeps a
+   client-side record of all devices, which includes basic information
+   about the device and also touchscreen tracking information, instead
+   of just scroll valuators.  */
+
 static void
 x_init_master_valuators (struct x_display_info *dpyinfo)
 {
@@ -11906,7 +11911,18 @@ handle_one_xevent (struct x_display_info *dpyinfo,
               device = xi_device_from_id (dpyinfo, device_changed->deviceid);
 
               if (!device)
-                emacs_abort ();
+                {
+                  /* An existing device might have been enabled.  */
+                  x_init_master_valuators (dpyinfo);
+
+                  /* Now try to find the device again, in case it was
+                     just enabled.  */
+                  device = xi_device_from_id (dpyinfo, device_changed->deviceid);
+                }
+
+              /* If it wasn't enabled, then stop handling this event.  */
+              if (!device)
+                goto XI_OTHER;
 
               /* Free data that we will regenerate from new
                  information.  */