use ZL and ZR to change songs with lid closed!

.vscode/c_cpp_properties.json

@@ -0,0 +1,23 @@
+{
+    "configurations": [
+        {
+            "name": "Win32",
+            "includePath": [
+                "${workspaceFolder}/**",
+                "${DEVKITPRO}/libctru/include",
+                "${DEVKITPRO}/devkitARM/arm-none-eabi/include"
+            ],
+            "defines": [
+                "_DEBUG",
+                "UNICODE",
+                "_UNICODE"
+            ],
+            "windowsSdkVersion": "10.0.22000.0",
+            "compilerPath": "cl.exe",
+            "cStandard": "c17",
+            "cppStandard": "c++17",
+            "intelliSenseMode": "windows-msvc-x64"
+        }
+    ],
+    "version": 4
+}

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+    "C_Cpp.errorSquiggles": "disabled"
+}

source/main.c

@@ -545,6 +545,18 @@ int main(int argc, char **argv)
 			}
 		}
 
+		if (kDown & KEY_ZR && fileNum < fileMax) {
+			fileNum += 1;
+			changeFile(dirList.files[fileNum - dirList.dirNum - 1], &playbackInfo);
+			continue;
+		}
+
+		if (kDown & KEY_ZL && fileNum > 0) {
+			fileNum -= 1;
+			changeFile(dirList.files[fileNum - dirList.dirNum - 1], &playbackInfo);
+			continue;
+		}
+
 		/* After 1000ms, update playback time. */
 		while(osGetTime() - mill > 1000)
 		{