Selecting a calendar requires permissions

app/src/main/java/eu/faircode/email/FragmentAccount.java

@@ -26,6 +26,7 @@ import static eu.faircode.email.ServiceAuthenticator.AUTH_TYPE_GMAIL;
 import static eu.faircode.email.ServiceAuthenticator.AUTH_TYPE_OAUTH;
 import static eu.faircode.email.ServiceAuthenticator.AUTH_TYPE_PASSWORD;
 
+import android.Manifest;
 import android.app.NotificationManager;
 import android.content.Context;
 import android.content.Intent;
@@ -437,6 +438,7 @@ public class FragmentAccount extends FragmentBase {
         });
 
         btnCalendar.setVisibility(BuildConfig.PLAY_STORE_RELEASE ? View.GONE : View.VISIBLE);
+        btnCalendar.setEnabled(Helper.hasPermission(getContext(), Manifest.permission.WRITE_CALENDAR));
         btnCalendar.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {