Need mutex to allow only 1 order open across multiple pairs

Hello,

I am looking for someone to code a "mutex" (see - http://articles.mql4.com/141) so that my EA when attached to multiple pairs will only allow 1 open order. I do have an open order limit already in my EA but this does not prevent multiple orders when they are sent at the exact same time. I will be providing a basic EA template for you to add the mutex functions to as this will allow me to use the mutex in my other EA's. I have tried to code a mutex myself but as the EA can send orders at the exact same time for some reason I cannot get it to stop opening more than 1 order simultaneously. It may be worth noting that on different charts the EA uses a different magic number but I believe that this should not affect the mutex. The mutex should wait until the end of the current bar as after then my open orders limit code will prevent the EA from opening any more trades. Basically, if the mutex causes the trade NOT to be sent at the exact time because there is already a trade being sent or existing then I DO NOT want it to try to open the order again. My EA works on the open of bars so the mutex must cater to this. If the EA is removed by the user or terminated cuasing an order to close or an order is closed manually then the global variable used should be set to "green light" to allow trading to continue.