WMR / WIN+Y / SteamVR ... losing controller focus

Whenever I launch my application (standalone exe) using SteamVR / WMR all goes well, (xbox-)controller works fine … until I put my headset on. When the headset sensor detects it's put on the blue "Win+Y" bar appears (annoyingly!). When I tap "Win-Y" my application no longer receives controller input. I must then manually click the SteamVR window and then back my own app, to get the controller working again.

This is obviously not acceptable for an end user. Yes, I could "tape" the sensor, but I can't really ask users to do that, can I?

I couldn't really find any workaround for that. Any ideas?

Geert