title: Android in-app billing: what is the "developer payload" and how the "Buy" button works?
body: <p>I am playing with the Google in-app billing example app "Dungeons".</p>
  
  <p>In this app, I can either click on the "Buy" button to buy something or on the "Edit Payload" button to...edit the payload :). But I don't understand what does this button and what "Edit Payload" means... Can anyone clarify that ?</p>
  
  <p>By the way, can anyone tell me how the "Buy" button fires the buying action as the code in the Dungeons app is the following (the buying action is launched by I don't understand how...):</p>
  
  <pre><code>public void onClick(View v) {
          if (v == mBuyButton) {
              // NO CODE HERE TO DO SOMETHING ???!!!
              if (!mBillingService.requestPurchase(mSku, mPayloadContents)) {
                  showDialog(DIALOG_BILLING_NOT_SUPPORTED_ID);
              }
          } else if (v == mEditPayloadButton) {
              showPayloadEditDialog();
          }
      }
  </code></pre>
  
  <p>Thanks !</p>