[wix-users] property not updated during maintenance

[Hagen Kant]

Hi,

first of all, thanks for the great tool set! 
While the wix toolset xml format itself is quite well documented, its a bit strange that - given the complexity of the concept - it lacks a comprehensive conceptual documentation, including lists of valid attributes values, when and how to schedule actions, etc., which probably causes the following question:

My WixUI_FeatureTree based installer has a custom dialog mounted between CustomizeDlg and VerifyReadyDlg which sets a property via ComboBox/ComboList. 

			<Control Id="Instances" Type="ComboBox" X="45" Y="135" Width="40" Height="18" Integer="yes" ComboList="yes" Sorted="yes" Property="INSTANCES">
				<ComboBox Property="INSTANCES">
					<ListItem Value="2"/>
					[...]
					<ListItem Value="12"/>
				</ComboBox>
			</Control>

The value is used in a deferred (elevated) custom .dll action:

			<CustomAction Id="UpdateInstances.SetProperty" Property="UpdateInstances" Value="[INSTANCES]"/>
			<CustomAction Id="UpdateInstances" Execute="deferred" Impersonate="no" BinaryKey="$(var.dll)" DllEntry="UpdateInstances"/>

scheduled via InstallExecuteSequence:

			<Custom Action="UpdateInstances.SetProperty" Before="UpdateInstances">NOT REMOVE</Custom>
			<Custom Action="UpdateInstances" Before="InstallFinalize">NOT REMOVE</Custom>
	
This works well for the install case, but for the maintenance ("modify") action it does not update the property. (it keeps its default.)

	<Property Id="INSTANCES" Value="2"/>

Any hint what could cause such a behaviour, or idea what to try is highly appreciated.

Thanks and best regards,
Hagen.