This function allows you to disable task switch through ALT+TAB or CTRL+ESC.
The only problem is viewers. If you have any viewers opened this function does not work.
So you can use this function only for mainWindow. 

to handle TaskSwitch mySwitch
        -- mySwitch = 1 - disable task switch
        -- mySwitch = 0 - enable task switch
        linkDLL "user"
                int LockInput(word,word,int)
        end linkDLL
        get lockInput(0,sysWindowHandle,mySwitch)
        unlinkDLL "user"
end