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SetFocus

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This function sets the keyboard focus to the specified window. All subsequent keyboard input is directed to this window. The window, if any, that previously had the keyboard focus loses it.

HWND SetFocus(
HWND hWnd );

Parameters

  • hWnd
    [in] Handle to the window that will receive the keyboard input. If this parameter is NULL, keystrokes are ignored.

Return Values

The handle to the window that previously had the keyboard focus indicates success. NULL indicates that the hWnd parameter is invalid or the window is not associated with the calling threads message queue. To get extended error information, call GetLastError.

Remarks

The SetFocus function sends a WM_KILLFOCUS message to the window that loses the keyboard focus and a WM_SETFOCUS message to the window that receives the keyboard focus. It also activates either the window that receives the focus or the parent of the window that receives the focus.

If a window is active but does not have the focus, any key pressed will produce the WM_SYSCHAR, WM_SYSKEYDOWN, or WM_SYSKEYUP message. If the VK_MENU key is also pressed, the lParam parameter of the message will have bit 30 set. Otherwise, the messages produced do not have this bit set.

Do not use the SetFocus function to set the keyboard focus to a window associated with another threads message queue. There is one exception. If a window on one thread is the child of the window on the other thread, or if the windows are siblings of the same parent, the thread associated with one window can set the focus to the other window even though it belongs to a different thread. In this case, there is no need to call AttachThreadInput first.

Requirements

Runs on Versions Defined in Include Link to
Windows CE OS 1.0 and later Winuser.h   Caret.lib, Foregnd.lib

Note   This API is part of the complete Windows CE OS package as provided by Microsoft. The functionality of a particular platform is determined by the original equipment manufacturer (OEM) and some devices may not support this API.

See Also

GetActiveWindow, GetFocus, GetLastError, SetActiveWindow, SetCapture, SetForegroundWindow, WM_KILLFOCUS, WM_SETFOCUS, WM_SYSCHAR, WM_SYSKEYDOWN, WM_SYSKEYUP

 Last updated on Tuesday, July 13, 2004

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