I think you should know your window handle ,otherwise , you can get it.<br> if so ,then you can do thing as follows :<br> first : call getwindowthreadId ,so you can get the threadid of your application you want to activate .<br> second : send message WM_ActiveApp ,then Activate your application<br> This is my first solution , if you want a better solution ,please <br>give me mord score , Ok !