diff --git a/app/src/main/cpp/emu48-jni.c b/app/src/main/cpp/emu48-jni.c
index 874ef24..4a3b86d 100644
--- a/app/src/main/cpp/emu48-jni.c
+++ b/app/src/main/cpp/emu48-jni.c
@@ -69,17 +69,32 @@ void mainViewResizeCallback(int x, int y) {
     }
 }
 
-void fillNullCharacter(const OPENFILENAME *ofn) {
-    TCHAR * pos = ofn->lpstrFilter;
+TCHAR * fillNullCharacter(TCHAR * fileFilter) {
+    TCHAR * pos = fileFilter;
+    int length = 0;
     if(pos) {
-        for (;;) {
+        for (;; pos++, length++) {
             if (*pos == 0) {
-                *pos = _T("|");
-                if (*(pos + 1) = 0)
+                if (*(pos + 1) == 0)
                     break;
             }
         }
+        TCHAR * newFileFilter = malloc(length + 1);
+        TCHAR * newPos = newFileFilter;
+        pos = fileFilter;
+        for (;; pos++, newPos++) {
+            if (*pos == 0) {
+                *newPos = _T('|');
+                if (*(pos + 1) == 0) {
+                    *(newPos + 1) = 0;
+                    break;
+                }
+            } else
+                *newPos = *pos;
+        }
+        return newFileFilter;
     }
+    return NULL;
 }
 
 int mainViewGetOpenFileNameCallback(OPENFILENAME * ofn) {
@@ -101,13 +116,15 @@ int mainViewGetOpenFileNameCallback(OPENFILENAME * ofn) {
 //
 //    ofn->nMaxFile = ARRAYSIZEOF(szBuffer);
 //    ofn->lpstrFile = szBuffer;
-    fillNullCharacter(ofn);
-    mainViewCallback(CALLBACK_TYPE_GETOPENFILENAME, ofn->nFilterIndex, ofn->Flags, ofn->lpstrFilter, ofn->lpstrDefExt);
+    TCHAR * lpstrFilter = fillNullCharacter(ofn->lpstrFilter);
+    mainViewCallback(CALLBACK_TYPE_GETOPENFILENAME, ofn->nFilterIndex, ofn->Flags, lpstrFilter, ofn->lpstrDefExt);
+    free(lpstrFilter);
 }
 
 int mainViewGetSaveFileNameCallback(OPENFILENAME * ofn) {
-    fillNullCharacter(ofn);
-    mainViewCallback(CALLBACK_TYPE_GETSAVEFILENAME, ofn->nFilterIndex, ofn->Flags, ofn->lpstrFilter, ofn->lpstrDefExt);
+    TCHAR * lpstrFilter = fillNullCharacter(ofn->lpstrFilter);
+    mainViewCallback(CALLBACK_TYPE_GETSAVEFILENAME, ofn->nFilterIndex, ofn->Flags, lpstrFilter, ofn->lpstrDefExt);
+    free(lpstrFilter);
 }
 
 
@@ -129,7 +146,10 @@ int mainViewCallback(int type, int param1, int param2, const TCHAR * param3, con
         jclass viewToUpdateClass = (*jniEnv)->GetObjectClass(jniEnv, viewToUpdate);
         //jmethodID midStr = (*jniEnv)->GetMethodID(jniEnv, viewToUpdateClass, "updateCallback", "()V");
         jmethodID midStr = (*jniEnv)->GetMethodID(jniEnv, viewToUpdateClass, "updateCallback", "(IIILjava/lang/String;Ljava/lang/String;)I");
-        int result = (*jniEnv)->CallIntMethod(jniEnv, viewToUpdate, midStr, type, param1, param2, param3, param4);
+        jstring utfParam3 = (*jniEnv)->NewStringUTF(jniEnv, param3);
+        jstring utfParam4 = (*jniEnv)->NewStringUTF(jniEnv, param4);
+        int result = (*jniEnv)->CallIntMethod(jniEnv, viewToUpdate, midStr, type, param1, param2, utfParam3, utfParam4);
+
 //        if(needDetach)
 //            ret = (*java_machine)->DetachCurrentThread(java_machine);
         return result;
diff --git a/app/src/main/java/com/regis/cosnier/emu48/MainActivity.java b/app/src/main/java/com/regis/cosnier/emu48/MainActivity.java
index f84213d..3bd0846 100644
--- a/app/src/main/java/com/regis/cosnier/emu48/MainActivity.java
+++ b/app/src/main/java/com/regis/cosnier/emu48/MainActivity.java
@@ -1,13 +1,17 @@
 package com.regis.cosnier.emu48;
 
+import android.app.Activity;
 import android.content.Intent;
+import android.net.Uri;
 import android.os.Bundle;
+import android.util.Log;
 import android.view.MotionEvent;
 import android.view.ViewGroup;
 import com.google.android.material.floatingactionbutton.FloatingActionButton;
 import com.google.android.material.navigation.NavigationView;
 import com.google.android.material.snackbar.Snackbar;
 
+import androidx.annotation.Nullable;
 import androidx.appcompat.app.ActionBarDrawerToggle;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.appcompat.widget.Toolbar;
@@ -17,11 +21,16 @@ import androidx.drawerlayout.widget.DrawerLayout;
 import android.view.View;
 import android.view.Menu;
 import android.view.MenuItem;
+import android.widget.Toast;
+
+import java.io.IOException;
+import java.io.OutputStream;
 
 public class MainActivity extends AppCompatActivity
         implements NavigationView.OnNavigationItemSelectedListener {
 
     private static final int INTENT_SETTINGS = 1;
+    private static final String TAG = "MainActivity";
     private MainScreenView mainScreenView;
 
     @Override
@@ -222,4 +231,25 @@ public class MainActivity extends AppCompatActivity
 
         super.onDestroy();
     }
+
+    @Override
+    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
+        if(requestCode == MainScreenView.INTENT_GETSAVEFILENAME && resultCode == Activity.RESULT_OK) {
+            Uri uri = data.getData();
+
+            //just as an example, I am writing a String to the Uri I received from the user:
+            Log.d(TAG, "onActivityResult INTENT_GETSAVEFILENAME " + uri.toString());
+
+//            try {
+//                OutputStream output = getContentResolver().openOutputStream(uri);
+//
+//                output.write(SOME_CONTENT.getBytes());
+//                output.close();
+//            }
+//            catch(IOException e) {
+//                Toast.makeText(this, "Error", Toast.LENGTH_SHORT).show();
+//            }
+        }
+        super.onActivityResult(requestCode, resultCode, data);
+    }
 }
diff --git a/app/src/main/java/com/regis/cosnier/emu48/MainScreenView.java b/app/src/main/java/com/regis/cosnier/emu48/MainScreenView.java
index f8eb982..5bb6952 100644
--- a/app/src/main/java/com/regis/cosnier/emu48/MainScreenView.java
+++ b/app/src/main/java/com/regis/cosnier/emu48/MainScreenView.java
@@ -243,7 +243,7 @@ public class MainScreenView extends SurfaceView {
     final int CALLBACK_TYPE_GETOPENFILENAME = 2;
     final int CALLBACK_TYPE_GETSAVEFILENAME = 3;
 
-    final int INTENT_GETSAVEFILENAME = 1;
+    public static int INTENT_GETSAVEFILENAME = 1;
     int updateCallback(int type, int param1, int param2, String param3, String param4) {
         switch (type) {
             case CALLBACK_TYPE_INVALIDATE:
@@ -259,7 +259,7 @@ public class MainScreenView extends SurfaceView {
             case CALLBACK_TYPE_GETSAVEFILENAME:
                 Intent intent = new Intent(Intent.ACTION_CREATE_DOCUMENT);
                 intent.addCategory(Intent.CATEGORY_OPENABLE);
-                intent.setType("YOUR FILETYPE"); //not needed, but maybe usefull
+                //intent.setType("YOUR FILETYPE"); //not needed, but maybe usefull
                 intent.putExtra(Intent.EXTRA_TITLE, "YOUR FILENAME"); //not needed, but maybe usefull
                 ((Activity)getContext()).startActivityForResult(intent, INTENT_GETSAVEFILENAME);
                 break;