title: Enable or disable the next button based on a live text control value in Wix?
body: <p>I created a custom dialog page in wix and it has a text box. I want to disable the next button of the installer if the text box is empty end enable it if the user has typed a value. The following code works partially. It does not disable the next button but it does not navigate to the next page unless you fill the value. The problem I have is that the status of the next button is not updated while you are typing a value in the edit text box. If I remove the value from the edit text box and then click back to the previous screen and then next, the next button is disabled.</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;Wix xmlns="http://schemas.microsoft.com/wix/2006/wi"&gt;
   &lt;Fragment&gt;
      &lt;UI&gt;
        &lt;Dialog Id="MyCustomDialog" Width="370" Height="270" Title="Custom Dialog Options"&gt;
          &lt;Control Id="Next" Type="PushButton" X="236" Y="243" Width="56" Height="17" Default="yes" Text="Next"&gt;
            &lt;Condition Action="disable"&gt;USERNAME1 = ""&lt;/Condition&gt;
            &lt;Condition Action="enable"&gt;NOT(USERNAME1 = "")&lt;/Condition&gt;
            &lt;Publish Event="NewDialog" Value="VerifyReadyDlg"&gt;NOT(USERNAME1 = "")&lt;/Publish&gt;
          &lt;/Control&gt;
          &lt;Control Id="Back" Type="PushButton" X="180" Y="243" Width="56" Height="17" Text="Back"&gt;
            &lt;Publish Event="NewDialog" Value="CustomizeDlg"&gt;1&lt;/Publish&gt;
          &lt;/Control&gt;
          &lt;Control Id="Cancel" Type="PushButton" X="304" Y="243" Width="56" Height="17" Cancel="yes" Text="Cancel"&gt;
            &lt;Publish Event="SpawnDialog" Value="CancelDlg"&gt;1&lt;/Publish&gt;
          &lt;/Control&gt;
  
          &lt;Control Id="Description" Type="Text" X="25" Y="23" Width="280" Height="15" Transparent="yes" NoPrefix="yes" Text="Please type the value" /&gt;
  
          &lt;Control Id="UserNameText" Type="Text" X="20" Y="60" Width="290" Height="13"  NoPrefix="yes" Text="Please type the username" /&gt;
          &lt;Control Id="UserNameEdit" Type="Edit" X="20" Y="72" Width="290" Height="18" Multiline="no" Property="USERNAME1"/&gt;
  
        &lt;/Dialog&gt;
      &lt;/UI&gt;
   &lt;/Fragment&gt;
  &lt;/Wix&gt;
  </code></pre>