Input: Fix stuck modifiers (bug #11683)

Disclaimer: It's 6:51am.  I'm trying to be as understandable as possible.

What was happening previously was this:
 * Press Alt
 * Extended event generated and processed: state is now Alt down once
 * Core event generated
   - keyboard switched: inherited state is Alt down once
   - event processed: Alt down twice
 * Release Alt
 * Extended event generated and processed: state is now null
 * Core event generated and processed: Alt down once

If we switch the order:
 * Press Alt
 * Core event generated:
  - keyboard switched: inherited state is null
  - event processed: Alt down once
 * Extended event generated and processed: state is now Alt down once
 * Release Alt
 * Core event generated and processed: state is now null
 * Extended event generated and processed: state is now null

When we carry over the previous state, it needs to be the _previous_ state
(state and modifiersPerKey), assuming that we're going to catch now-core
events for any of these.  For example, if Ctrl is held down as we pivot, we
need to carry Ctrl over with a count of one, for which an extended + core
release will then clear.  Carrying over the union of the previous state _and
the state resulting from the immediate action_ was what broke things.

1 files changed, 28 insertions, 26 deletions

diff --git a/dix/getevents.c b/dix/getevents.c
index bc3db7919..2a10038bc 100644
--- a/dix/getevents.c
+++ b/dix/getevents.c
@@ -445,6 +445,13 @@ GetKeyboardValuatorEvents(xEvent *events, DeviceIntPtr pDev, int type,
 
     ms = GetTimeInMillis();
 
+    if (pDev->coreEvents) {
+        events->u.keyButtonPointer.time = ms;
+        events->u.u.type = type;
+        events->u.u.detail = key_code;
+        events++;
+    }
+
     kbp = (deviceKeyButtonPointer *) events;
     kbp->time = ms;
     kbp->deviceid = pDev->id;
@@ -462,12 +469,6 @@ GetKeyboardValuatorEvents(xEvent *events, DeviceIntPtr pDev, int type,
                                    num_valuators, valuators);
     }
 
-    if (pDev->coreEvents) {
-        events->u.keyButtonPointer.time = ms;
-        events->u.u.type = type;
-        events->u.u.detail = key_code;
-    }
-
     return numEvents;
 }
 
@@ -606,8 +607,27 @@ GetPointerEvents(xEvent *events, DeviceIntPtr pDev, int type, int buttons,
     pDev->valuator->lastx = x;
     pDev->valuator->lasty = y;
 
-    if (!coreOnly)
-    {
+    /* for some reason inputInfo.pointer does not have coreEvents set */
+    if (coreOnly || pDev->coreEvents) {
+        events->u.u.type = type;
+        events->u.keyButtonPointer.time = ms;
+        events->u.keyButtonPointer.rootX = x;
+        events->u.keyButtonPointer.rootY = y;
+
+        if (type == ButtonPress || type == ButtonRelease) {
+            /* We hijack SetPointerMapping to work on all core-sending
+             * devices, so we use the device-specific map here instead of
+             * the core one. */
+            events->u.u.detail = pDev->button->map[buttons];
+        }
+        else {
+            events->u.u.detail = 0;
+        }
+
+        events++;
+    }
+
+    if (!coreOnly) {
         kbp = (deviceKeyButtonPointer *) events;
         kbp->time = ms;
         kbp->deviceid = pDev->id;
@@ -635,24 +655,6 @@ GetPointerEvents(xEvent *events, DeviceIntPtr pDev, int type, int buttons,
         }
     }
 
-    /* for some reason inputInfo.pointer does not have coreEvents set */
-    if (coreOnly || pDev->coreEvents) {
-        events->u.u.type = type;
-        events->u.keyButtonPointer.time = ms;
-        events->u.keyButtonPointer.rootX = x;
-        events->u.keyButtonPointer.rootY = y;
-
-        if (type == ButtonPress || type == ButtonRelease) {
-            /* We hijack SetPointerMapping to work on all core-sending
-             * devices, so we use the device-specific map here instead of
-             * the core one. */
-            events->u.u.detail = pDev->button->map[buttons];
-        }
-        else {
-            events->u.u.detail = 0;
-        }
-    }
-
     return num_events;
 }