To reproduce, open a Factorio world and run these commands:
Code: Select all
/c x = game.player.gui.center.add{type="frame"}
/c x.style.width = 200
/c x.style.height = 200
/c x.elem_tooltip = {type = "signal", name = "uranium-processing", signal_type = "recipe"}
According to the ElemID documentation, the signal_type field is required.
SignalIDType can be one of eight possible strings, but only "virtual" signal_type with an accompanying virtual signal as "name" will show a tooltip, like so:
Code: Select all
/c x.elem_tooltip = {type = "signal", name = "up-arrow", signal_type = "virtual"}

