/ This function cannot retrieve the text of an edit control in another application. To get extended error information, call GetLastError. / or control handle is invalid, the return value is zero. If the window has no title bar or text, if the title bar is empty, or if the window / If the function succeeds, the return value is the length, in characters, of the copied string, not including If the text exceeds this limit, it is truncated. / to the buffer, including the null character.

/ the string is as long or longer than the buffer, the string is truncated and terminated with a null character. Type: LPTSTR )The buffer that will receive the text. Type: HWND )A handle to the window or control containing the text. However, GetWindowText cannot retrieve the text of a control in another / control, the text of the control is copied. / Copies the text of the specified window's title bar (if it has one) into a buffer.

To retrieve the text of a possibly unresponsive control in the same process, use SendMessageTimeout with a WM_GETTEXT message instead. To retrieve the text of a control in another process, send a WM_GETTEXT message directly instead of calling GetWindowText. However, if the target window is not responding and it belongs to the calling application, GetWindowText will cause the calling application to become unresponsive. It allows applications to call GetWindowText without becoming unresponsive if the process that owns the target window is not responding. If the window does not have a caption, the return value is a null string. If the target window is owned by another process and has a caption, GetWindowText retrieves the window caption text.

Getwindowtext delphibasics