wix Managed Bootstrapper: Engine.EvaluateCondition() requires separate thread? - wix

Question

In my Managed Bootstrapper, I tried to call Engine.EvaluateCondition("MY_PROG_FOUND"); in Run() method. But it never evaluates and said something like: "This requires a running thread." and it never evaluates.
I'm trying to evaluate Bundle conditions in my managed bootstrapper but still no luck.
MY_PROG_FOUND is defined in Bundle code:
<util:RegistrySearch Id="PETRELINSTALLLOCATION"
Variable="MY_PROG_FOUND"
Root="HKLM"
Key="SYSTEM\CurrentControlSet\Control\Session Manager\Environment"
Value="$(var.my_prog_env_var)"
Result="exists"
/>
<bal:Condition Message="[WixBundleName] required the installation of My Program.">
<![CDATA[Installed OR (MY_PROG_FOUND)]]>
</bal:Condition>
How can I use Engine.EvaluateCondition() in managed bootstrapper? Does this requires to be called in a specific event, like DetectBegin()??
Any help would be really appreciated...
Thanks a bunch.

Answer 1

Later I figured out that the separate thread is active during event calls. So I tried it during DetectComplete event and it worked. But before that, I had to parse BootstrapperApplicationData.xml file to get WixBalCondition elements and get the collection into an array e.g. BalConditions[].
Here is my code snippet:
void BootstrapperApplication_DetectComplete(object sender, DetectCompleteEventArgs e)
{
string balCondtionMessages = string.Empty;
bool balConditionStatus = true;
foreach (var balCondition in bootAppData.BundleData.BalConditions)
{
if (!model.BootstrapperApplication.Engine.EvaluateCondition(balCondition.Condition))
{
balConditionStatus = false;
if (!String.IsNullOrEmpty(balCondtionMessages))
{
balCondtionMessages = balCondtionMessages + '\n' + "- " + balCondition.Message;
}
else
balCondtionMessages = "- " + balCondition.Message;
}
}
if (!balConditionStatus)
{
SetbalConditionMsg(balCondtionMessages);
}
}
This makes us parse for all conditions in our Bundle.wxs code, evaluate them and display the related message in our Custom Bootstrapper UI.