Unfortunately there is nothing you can do within Wix# to fix this. The initialization of the UI is completely under control of MSI and WiX runtime.
The easiest solution would be to extend your custom UI code to preposition itself at startup. Though it can be some special setting in the IEmbeddedUI interface (WiX DTF) that addresses the problem.
The easiest solution would be to extend your custom UI code to preposition itself at startup. Though it can be some special setting in the IEmbeddedUI interface (WiX DTF) that addresses the problem.