title: Cancel selection of combobox in SAPUI5
body: <p>I have a combo box and I want to throw a message with a fallback logic, in case he selects something, he should get a warning, if he presses okay it executes the logic, if he does not it should be canceled.</p>
  
  <pre><code>&lt;ComboBox id="id1" change="onChange"&gt;
      &lt;core:Item id="id2" text="A"&gt;&lt;/core:Item&gt;
      &lt;core:Item id="id3" text="B"&gt;&lt;/core:Item&gt;
      &lt;core:Item id="id4" text="C"&gt;&lt;/core:Item&gt;
  &lt;/ComboBox&gt;
  </code></pre>
  
  <p>then I have my <code>messagebox</code> in the <code>onChange</code> function:</p>
  
  <pre><code>onChange: function (oEvent) {
      sap.m.MessageBox.show("Are you sure you want to do that?", {
          icon: sap.m.MessageBox.Icon.Information,
          title: "Info",
          actions: [sap.m.MessageBox.Action.YES, sap.m.MessageBox.Action.NO],
          defaultAction: sap.m.MessageBox.Action.NO,
          onClose: function (sButton) {
              if (sButton === sap.m.MessageBox.Action.YES) {
                  //execute my logic in here =&gt; that works
              } else {
                  oEvent.stopPropagation(); //I tried this but this does not work
              }
          }
      });
  }
  </code></pre>
  
  <p>how can I achieve that?</p>
  
  <p>In other words, all I would actually need is to know what the predecessor selection of that <code>combobox</code> was. </p>
  
  <p>I did not find out how to get that out of the <code>oEvent</code>.</p>