diff --git a/examples/Makefile b/examples/Makefile
index 679b707..b7847e8 100644
--- a/examples/Makefile
+++ b/examples/Makefile
@@ -40,7 +40,7 @@ LDLIBS    = -lwiringPi -lwiringPiDev -lpthread -lm -lcrypt -lrt
 
 SRC	= \
   blink12.c blink12drcs.c blink6drcs.c blink8.c blink8-drcn.c blink.c blink-thread.c \
-  buttons.c buttons2.c buttons3.c \
+  buttons.c buttons2.c buttons3.c buttons4.c \
   clock.c \
   delayTest.c \
   ds1302.c \
diff --git a/examples/buttons4.c b/examples/buttons4.c
new file mode 100644
index 0000000..cf20c98
--- /dev/null
+++ b/examples/buttons4.c
@@ -0,0 +1,197 @@
+/*
+ * buttons4.c:
+ *	Multiple button handling with debounce.
+ *
+ ***********************************************************************
+ * This file is part of wiringPi:
+ *      https://github.com/nuncio-bitis/WiringPi
+ *
+ *    wiringPi is free software: you can redistribute it and/or modify
+ *    it under the terms of the GNU Lesser General Public License as published
+ *by the Free Software Foundation, either version 3 of the License, or (at your
+ *option) any later version.
+ *
+ *    wiringPi is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Lesser General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Lesser General Public License
+ *    along with wiringPi.  If not, see <http://www.gnu.org/licenses/>.
+ ***********************************************************************
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+#include <unistd.h>
+#include <errno.h>
+#include <pthread.h>
+
+#include <wiringPi.h>
+
+//**********************************************************************************************************************
+
+// Define the GPIOs (BCM) that buttons are attached to.
+// Button1, Button2, ... , ButtonN-1
+static const int buttonGpios[] = { 26, 16, 20, 21 };
+
+// Button flags: 1 = button was pressed.
+// @NOTE The size of this array must match the number of GPIOs specified in buttonGpios above
+static int buttons[4];
+
+static const int nButtons = (sizeof (buttonGpios) / sizeof (int));
+
+// Debounce time in mS
+#define DEBOUNCE_TIME 50
+
+static int terminate_process = 0;
+
+//**********************************************************************************************************************
+
+static void Signal_handler(int sig);
+
+//**********************************************************************************************************************
+
+/* debounce
+ *  Thread to monitor button GPIOs and debounce them.
+ */
+static void *debounce (UNUSED void *arg)
+{
+    int masks[nButtons];
+    int button_times[nButtons];
+
+    // Set the GPIOs as inputs
+    // Also set up the gpio bank masks for each button
+    for (int i = 0; i < nButtons; ++i)
+    {
+        pinMode (buttonGpios[i], INPUT);
+        pullUpDnControl (buttonGpios[i], PUD_UP);
+
+        // Set up GPIO masks for the GPIO bank
+        masks[i] = (1 << buttonGpios[i]);
+
+        // Clear button flags and counters
+        buttons[i] = 0;
+        button_times[i] = 0;
+    }
+
+    // --------------------------------
+    // GPIO monitor & debounce loop
+    uint32_t bank0 = 0;
+    uint32_t prev_button_states[nButtons];
+
+    while (!terminate_process)
+    {
+        usleep(5 * 1000);
+
+        bank0 = digitalReadBank(0);
+
+        for (int i=0; i < nButtons; ++i)
+        {
+            int buttonState = (bank0 & masks[i]);
+
+            // If button changed state, reset its timer.
+            if (buttonState != prev_button_states[i])
+            {
+                button_times[i] = millis();
+            }
+
+            if ((millis() - button_times[i]) >= DEBOUNCE_TIME)
+            {
+                // Pressed button = LOW = 0
+                // Set the state to 1 if pressed, 0 if released.
+                buttons[i] = !buttonState;
+            }
+
+            prev_button_states[i] = buttonState;
+        }
+    } // end while
+
+    // --------------------------------
+
+    printf("Debounce done.\n");
+
+    return (void *)NULL;
+}
+
+//**********************************************************************************************************************
+
+static void Button_Wait (int pin)
+{
+    printf(" %-2d  %-2d  %-2d  %-2d\n", buttons[0], buttons[1], buttons[2], buttons[3]);
+}
+
+//**********************************************************************************************************************
+
+int main (int argc, char *argv[])
+{
+    // Set the handler for SIGTERM (15)
+    signal(SIGTERM, Signal_handler);
+    signal(SIGHUP,  Signal_handler);
+    signal(SIGINT,  Signal_handler);
+    signal(SIGQUIT, Signal_handler);
+    signal(SIGTRAP, Signal_handler);
+    signal(SIGABRT, Signal_handler);
+    signal(SIGALRM, Signal_handler);
+    signal(SIGUSR1, Signal_handler);
+    signal(SIGUSR2, Signal_handler);
+
+    printf ("Raspberry Pi Button Test\n");
+
+    // ----------------------------------------------------
+
+    // Set up for BCM pin numbering
+    wiringPiSetupGpio ();
+
+    // ----------------------------------------------------
+    // Set up the button debounce thread
+
+    pthread_t debounceThreadId;
+    pthread_create (&debounceThreadId, NULL, debounce, NULL) ;
+
+    // ----------------------------------------------------
+
+    // Set up a callback for when any of these buttons is pressed/released
+    // The ISR will display the state of all buttons.
+    if (wiringPiISRmulti ((int *)buttonGpios, nButtons, INT_EDGE_RISING, &Button_Wait) < 0)
+    {
+        fprintf (stderr, "%s: Unable to setup ISR: %s\n", argv[0], strerror(errno));
+        return EXIT_FAILURE;
+    }
+
+    // ----------------------------------------------------
+
+    printf("Buttons:\n");
+    printf(" 1   2   3   4\n");
+    printf("--- --- --- ---\n");
+    while (!terminate_process)
+    {
+        delayMs(100);
+    }
+
+    // ----------------------------------------------------
+
+    pthread_join(debounceThreadId, NULL);
+
+    printf("%s done.\n", argv[0]);
+
+    return EXIT_SUCCESS;
+}
+
+//**********************************************************************************************************************
+
+/**
+ * Intercepts and handles signals from QNX
+ * This function is called when the SIGTERM signal is raised by QNX
+ */
+static void Signal_handler(int sig)
+{
+  printf("Received signal %d\n", sig);
+
+  // Signal process to exit.
+  terminate_process = 1;
+}
+
+//**********************************************************************************************************************
diff --git a/wiringPi/wiringPi.h b/wiringPi/wiringPi.h
index 7eff836..2d4f382 100644
--- a/wiringPi/wiringPi.h
+++ b/wiringPi/wiringPi.h
@@ -278,6 +278,7 @@ extern void digitalWriteByte2   (int value);
 // Set up for a callback to be called when the specified pin changes according to mode.
 // mode = INT_EDGE_SETUP, INT_EDGE_FALLING, INT_EDGE_RISING, INT_EDGE_BOTH
 // Uses SYS mode, and also waitForInterrupt
+// @NOTE: This leaves gpios exported in /sys/class/gpio when the program ends.
 extern int  wiringPiISR         (int pin, int mode, void (*function)(int));
 
 // Same as wiringPiISR above, but takes a list of pins to wait for.
@@ -287,6 +288,7 @@ extern int  wiringPiISRmulti    (int pins[], int n_pins, int mode, void (*functi
 // Internal-only (unless you know how to set up /sys/class/gpio)
 // Wait for "interrupt" on a GPIO pin.
 // Must be in SYS mode (wiringPiSetupSys was called for setup)
+// @NOTE: This leaves gpios exported in /sys/class/gpio when the program ends.
 extern int  waitForInterrupt    (int pin, int mS);
 
 // ----------------------------------------------------------------------------