Don't interrupt active gesture input by modifier key presses.

They're likely to be caused by palm touches.

Change-Id: Ic1e0b86c5bf5d4c22f888f0bb77342584e45763e
Signed-off-by: Mohammad Hasan Keramat J <ikeramat@protonmail.com>

java/src/com/android/inputmethod/keyboard/PointerTracker.java

@@ -636,9 +636,14 @@ public final class PointerTracker implements PointerTrackerQueue.Element,
         final Key key = getKeyOn(x, y);
         mBogusMoveEventDetector.onActualDownEvent(x, y);
         if (key != null && key.isModifier()) {
-            // Before processing a down event of modifier key, all pointers already being
-            // tracked should be released.
-            sPointerTrackerQueue.releaseAllPointers(eventTime);
+            if (sInGesture) {
+                // Make sure not to interrupt an active gesture
+                return;
+            } else {
+                // Before processing a down event of modifier key, all pointers
+                // already being tracked should be released.
+                sPointerTrackerQueue.releaseAllPointers(eventTime);
+            }
         }
         sPointerTrackerQueue.add(this);
         onDownEventInternal(x, y, eventTime);