Win32 to Copy User-Selected Text

I've been struggling for a while now with retrieving the highlighted/selected text from a window. I've used:

GetForegroundWindow
GetCursorPos
WindowFromPoint
SendMessage(... GETTEXT...)/SendMessage(...GETSELTEXT...)

But the best I can do is on some windows get back the entire text. In Word, IE, Firefox, etc. I get nothing back. I'm using C# to make the API calls but if anyone knows how to do it in any language, I would appreciate it.

 

I dont use other window than mine.
You have to use THEIR dll´s.

 

I mean: I dont use foreign windows and their content.
You have to include the DLLs for eg. IE or Firefox.
Then you can retrieve a handler to that window and read the context.