hammerspoon script for Focus Follows Mouse behavior on macos (install hammerspoon, Open Config from menu)

init.lua

-- Focus follows mouse
local lastWinElement = nil

local function focusCheck()
    local ok, err = pcall(function()
        local mousePos = hs.mouse.absolutePosition()
        
        local systemWide = hs.axuielement.systemWideElement()
        local elementAtPoint = systemWide:elementAtPosition(mousePos)
        
        if elementAtPoint then
            local element = elementAtPoint
            local windowElement = nil
            
            while element do
                local role = element:attributeValue("AXRole")
                if role == "AXWindow" then
                    windowElement = element
                    break
                end
                element = element:attributeValue("AXParent")
            end
            
            if windowElement then
                local winTitle = windowElement:attributeValue("AXTitle") or ""
                local pid = windowElement:pid()
                local winKey = tostring(pid) .. ":" .. winTitle
                
                if winKey ~= lastWinElement then
                    lastWinElement = winKey
                    
                    local app = hs.application.applicationForPID(pid)
                    if app then
                        windowElement:performAction("AXRaise")
                        app:activate(false)
                        -- print("Focused: " .. app:name() .. " - " .. winTitle)
                    end
                end
            end
        end
    end)
    
    -- if not ok then
    --     print("Error: " .. tostring(err))
    -- end
    
    -- Always schedule next check
    hs.timer.doAfter(0.1, focusCheck)
end

-- Start the chain
focusCheck()

hs.alert.show("Focus follows mouse enabled")