Hello everybody, I want to implement something like we do it many times, suppose Media Player is open and playing a music now for example I want to do this File-->Properties when I do that,Properties window will open now I want to implement it in my application exactly I did as below(with help of this link http://www.codeproject.com/csharp/wmp_pinvoke.asp) [code] public const int WM_COMMAND = 0x111; [DllImport("User32.dll")] public static extern Int32 SendMessage(int hWnd, int Msg,int wParam, int lParam); private void button1_Click(object sender, System.EventArgs e) { int iHandle=0x00010120;//the handle of Media Player Form1.SendMessage(iHandle, Form1.WM_COMMAND,0x0000495b, 0x00000000); //0x0000495b results in showing Properties Window } [/code] But here there is a problem it nicely open the propertise window but my program is hanged after it I can get what is the cause of this problem (I guess SendMessage cant return properly when I use PostMessage instead my application is not hanged but it doesnt work correctly and give me wrong results) can anybody give me an idea?, any help is appreciated.