Fix #134733: NDOF jumps when switching between applications

Window de-activation wasn't reliably clearing the NDOF motion state.

See code-comments for details.

intern/ghost/intern/GHOST_NDOFManager.cc

@@ -674,6 +674,17 @@ static bool nearHomePosition(const GHOST_TEventNDOFMotionData *ndof, float thres
 bool GHOST_NDOFManager::sendMotionEvent()
 {
   if (!motion_event_pending_) {
+    if (motion_state_ != GHOST_kNotStarted) {
+      /* Detect window de-activation and change the `motion_state_` even when no motion is pending.
+       * Without this check it's possible the window is de-activated before the NDOF
+       * motion callbacks have run, while the `motion_state_` is active.
+       * In this case, activating the window again would create an event
+       * with a large time-delta, see: #134733. */
+      if (system_.getWindowManager()->getActiveWindow() == nullptr) {
+        /* Avoid large `dt` times when changing windows. */
+        motion_state_ = GHOST_kNotStarted;
+      }
+    }
     return false;
   }