Same OS Thread - andlabs/ui GitHub Wiki

You need to keep your updates to the UI on the same OS thread. Be careful using go foo() and then updating the UI from foo(). One fix is to create a handler that keeps the whole execution in the same thread.

Use ui.QueueMain when updating the UI from another goroutine: https://github.com/andlabs/ui/wiki/Update-your-UI-in-other-goroutine