Implementing Callback Functions
The secret life of GetWindowText
“GetWindowText() cannot retrieve text from a window from another application.”
Difference between WM_GETTEXT and GetWindowText?
Question: What is the difference between sending message WM_GETTEXT and calling GetWindowText()?
Answer: You can send WM_GETTEXTLENGTH and WM_GETTEXT message even across processes. GetWindowText takes shortcuts, it tries to directly pass a WM_GETTEXT message to the target windows window function instead of using SendMessage. That does not work across process boundaries.