Confirm showing images in composer

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

@@ -915,9 +915,18 @@ public class FragmentCompose extends FragmentBase {
         ibReferenceImages.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
+                new AlertDialog.Builder(v.getContext())
+                        .setMessage(R.string.title_ask_show_image)
+                        .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+                            @Override
+                            public void onClick(DialogInterface dialog, int which) {
                                 ibReferenceImages.setVisibility(View.GONE);
                                 onReferenceImages();
                             }
+                        })
+                        .setNegativeButton(android.R.string.cancel, null)
+                        .show();
+            }
         });
 
         etBody.setTypeface(StyleHelper.getTypeface(compose_font, getContext()));