intellisense type dropdown as a third party tool

I am developing a third party intellisense tool using Visual C++.

I am placing a listbox on a dialog and showing it in keypress(using Win32 hooking). This dialog will show up in any texteditor(notepad开发者_StackOverflow中文版,powerpoint,etc). The list will have all the features of the intellisense dropdown as we see in Visual Studio except suggestions(the list is static). The dropdown will every time show a static list of values read from a xml file. User can choose an item from the dropdown and close it.

Please tell me what is the window style i need to use. I tried WS_EX_NOACTIVATE. but the dialog still gaining focus when displayed.

Thanks, JOhn