Can you please not take away the primary UI of a building while it is being upgraded? We are unable to disable or change the production priorities of a building while it is being upgraded. The building continues to function, as I have seen a guard stockpiling during an upgrade. In this instance, I was unable to turn off that guard house due to construction. Other buildings that have multiple items of production with sliders would be stuck as you last had them during construction.
All we really need is in the regular UI where the Upgrade button is shown to instead be disabled with text saying it is upgrading. Maybe that can be a progress bar too. Of course the option to prioritize or halt the upgrade would need to find a place on that UI as well.
If you really want to preserve the work that went in to making the upgrade UI, then just add it as a slide out window on the left of the primary UI (can have a pull tab)
The same can be said for buildings being moved where the destination site needs clearing first.