Hammerspoon function to move off-screen windows onto the main screen

rescuewindows.lua

-- Rescue Windows
-- Move any windows that are off-screen onto the main screen
function rescueWindows()
    local screen = hs.screen.mainScreen()
    local screenFrame = screen:fullFrame()
    local wins = hs.window.visibleWindows()
    for i,win in ipairs(wins) do
        local frame = win:frame()
        if not frame:inside(screenFrame) then
            win:moveToScreen(screen, true, true)
        end
    end
end

return rescueWindows

In init.lua:

rescueWindows = require "rescuewindows"
hs.hotkey.bind({"cmd", "alt", "ctrl"}, "R", rescueWindows)