Issue: `gui/quickfort` smooth designations invisible

[Bumber64]

Using a smoothing blueprint with gui/quickfort can seem to do nothing when placed, due to DF not showing the designations in the default view until a tick has passed.

We could:

1. Force the game into smoothing mode so the player can see them
2. Render our own overlay (like with aquifers)
3. Give a warning popup if not in smoothing mode

[SilasD]

DFHack already has an overlay to display smoothing designations in ASCII mode.

It's in plugins/dig.cpp, and the main function is paintScreenDesignated().

It appears to be activated by the overlay module plugins/lua/dig.lua.

there might be a way to tickle that module to get the smoothing display working,
or perhaps just adding another focus_path case to its viewscreens triggers,
and getting blueprint to set that focus_path while placing a blueprint.

Edit: I can't find an example of explicitly setting a focus_path in any script.
I'm only finding overlays. Perhaps I'm not using the right keywords.