This function changes the text of the specified window's title bar, if it has one. If the specified window is a control, the text of the control is changed.
Nonzero indicates success. Zero indicates failure. To get extended error information, call GetLastError.
If the target window is owned by the current process, SetWindowText causes a WM_SETTEXT message to be sent to the specified window or control. If the control is a list box control created with the WS_CAPTION style, however, SetWindowText sets the text for the control, not for the list box entries.
The SetWindowText function does not expand tab characters (ASCII code 0x09). Tab characters are displayed as vertical bar (|) characters.
Calling SetWindowText with any amount of text will cause the control to initialize to UNICODE. Calling SetWindowText with empty text will not cause the control to initialize to UNICODE.