Don't send the initial joystick axis event if the application is in the background

src/joystick/SDL_joystick.c

@@ -1344,7 +1344,7 @@ SDL_PrivateJoystickAxis(SDL_Joystick *joystick, Uint8 axis, Sint16 value)
         info->value = value;
         info->zero = value;
         info->has_initial_value = SDL_TRUE;
-    } else if (value == info->value) {
+    } else if (value == info->value && !info->sending_initial_value) {
         return 0;
     } else {
         info->has_second_value = SDL_TRUE;
@@ -1356,15 +1356,17 @@ SDL_PrivateJoystickAxis(SDL_Joystick *joystick, Uint8 axis, Sint16 value)
             return 0;
         }
         info->sent_initial_value = SDL_TRUE;
-        info->value = ~value; /* Just so we pass the check above */
+        info->sending_initial_value = SDL_TRUE;
         SDL_PrivateJoystickAxis(joystick, axis, info->initial_value);
+        info->sending_initial_value = SDL_FALSE;
     }
 
     /* We ignore events if we don't have keyboard focus, except for centering
      * events.
      */
     if (SDL_PrivateJoystickShouldIgnoreEvent()) {
-        if ((value > info->zero && value >= info->value) ||
+        if (info->sending_initial_value ||
+            (value > info->zero && value >= info->value) ||
             (value < info->zero && value <= info->value)) {
             return 0;
         }

src/joystick/SDL_sysjoystick.h

@@ -36,6 +36,7 @@ typedef struct _SDL_JoystickAxisInfo
     SDL_bool has_initial_value; /* Whether we've seen a value on the axis yet */
     SDL_bool has_second_value;  /* Whether we've seen a second value on the axis yet */
     SDL_bool sent_initial_value; /* Whether we've sent the initial axis value */
+    SDL_bool sending_initial_value; /* Whether we are sending the initial axis value */
 } SDL_JoystickAxisInfo;
 
 typedef struct _SDL_JoystickTouchpadFingerInfo