diff --git a/uisimulator/sdl/lcd-bitmap.c b/uisimulator/sdl/lcd-bitmap.c
index d0c4b4c..0469699 100644
--- a/uisimulator/sdl/lcd-bitmap.c
+++ b/uisimulator/sdl/lcd-bitmap.c
@@ -75,6 +75,7 @@ void lcd_update_rect(int x_start, int y_start, int width, int height)
 void sim_backlight(int value)
 {
     lcd_backlight_val = value;
+    fprintf(stderr, "sim_backlight(%i)\n", value);
 
 #if LCD_DEPTH <= 8
     if (value > 0) {
diff --git a/uisimulator/sdl/button.c b/uisimulator/sdl/button.c
index efa20da..0b53f82 100644
--- a/uisimulator/sdl/button.c
+++ b/uisimulator/sdl/button.c
@@ -796,6 +796,9 @@ void button_event(int key, bool pressed)
                         else
                         {
 #endif
+                            fprintf(stderr, "bl_on=%i ffkp=%i btn=%08X bbm=%08X btn&bbm=%08X\n",
+                                            (int)is_backlight_on(), (int)filter_first_keypress,
+                                            (int)btn, (int)backlight_on_button_mask, (int)(btn & backlight_on_button_mask));
                             if (is_backlight_on() || !filter_first_keypress
                                     || (filter_first_keypress && !(btn & backlight_on_button_mask)))
                                 queue_post(&button_queue, btn, data);