原文:
If the target window is owned by the current process, GetWindowText causes a WM_GETTEXT message to be sent to the specified window or control. If the target window is owned by another process and has a caption, GetWindowText retrieves the window caption text. If the window does not have a caption, the return value is a null string. This behavior is by design. It allows applications to call GetWindowText without hanging if the process that owns the target window is hung. However, if the target window is hung and it belongs to the calling application, GetWindowText will hang the calling application.
To retrieve the text of a control in another process, send a WM_GETTEXT message directly instead of calling GetWindowText.
