Когда мышка кликает по твоему окну, и оно не активно. Виндовс активизирует окно и посылает сообшение окну WM_ACTIVATE. Я предлагаю перехватывать это сообшение.
The WM_ACTIVATE message is sent when a window is being activated or deactivated. This message is sent first to the window procedure of the top-level window being deactivated; it is then sent to the window procedure of the top-level window being activated.
WM_ACTIVATE
fActive = LOWORD(wParam); // activation flag
fMinimized = (BOOL) HIWORD(wParam); // minimized flag
hwndPrevious = (HWND) lParam; // window handle
Parameters
fActive
Value of the low-order word of wParam. Specifies whether the window is being activated or deactivated. This parameter can be one of the following values:
Value Meaning
WA_ACTIVE Activated by some method other than a mouse click (for example, by a call to the SetActiveWindow function or by use of the keyboard interface to select the window).
WA_CLICKACTIVE Activated by a mouse click.
WA_INACTIVE Deactivated.
fMinimized
Value of the high-order word of wParam. Specifies the minimized state of the window being activated or deactivated. A nonzero value indicates the window is minimized.
hwndPrevious
Value of lParam. Identifies the window being activated or deactivated, depending on the value of the fActive parameter. If the value of fActive is WA_INACTIVE, hwndPrevious is the handle of the window being activated. If the value of fActive is WA_ACTIVE or WA_CLICKACTIVE, hwndPrevious is the handle of the window being deactivated. This handle can be NULL.
Return Values
If an application processes this message, it should return zero.
Default Action
If the window is being activated and is not minimized, the DefWindowProc function sets the keyboard focus to the window.
Remarks
If the window is activated by a mouse click, it also receives a WM_MOUSEACTIVATE message.
Да кстати обрати внимание:
The WM_ACTIVATE message is sent when a window is being activated or deactivated. This message is sent first to the window procedure of the top-level window being deactivated; it is then sent to the window procedure of the top-level window being activated. т.е. оно будет приходить дважды, сначало на активацию, затем на дезактивацию. Нужно смотреть на флаг fActive, который придет вместе с сообшением.
Активизируеш предыдушее окно, его хэндл хранится в hwndPrevious. При помоши функции
The SetActiveWindow function activates a window.
HWND SetActiveWindow(
HWND hWnd // handle of window to activate
);
Parameters
hWnd
Identifies the top-level window to be activated.
Return Values
If the function succeeds, the return value is the handle of the window that was previously active.
Remarks
The SetActiveWindow function activates a window, but not if the application is in the background. The window will be brought into the foreground (top of Z order) if the application is in the foreground when it sets the activation.
If the window identified by the hWnd parameter was created by the calling thread, the active window status of the calling thread is set to hWnd. Otherwise, the active window status of the calling thread is set to NULL.
The SetForegroundWindow window function, on the other hand, activates a window and forces it into the foreground. An application should only call SetForegroundWindow if it needs to display critical errors or information that needs the user's immediate attention .
Затем выставляеш Z уровень своего окна при помоши
The SetWindowPos function changes the size, position, and Z order of a child, pop-up, or top-level window. Child, pop-up, and top-level windows are ordered according to their appearance on the screen. The topmost window receives the highest rank and is the first window in the Z order.
BOOL SetWindowPos(
HWND hWnd, // handle of window
HWND hWndInsertAfter, // placement-order handle
int X, // horizontal position
int Y, // vertical position
int cx, // width
int cy, // height
UINT uFlags // window-positioning flags
);
Parameters
hWnd
Identifies the window.
hWndInsertAfter
Identifies the window to precede the positioned window in the Z order. This parameter must be a window handle or one of the following values:
Value Meaning
HWND_BOTTOM Places the window at the bottom of the Z order. If the hWnd parameter identifies a topmost window, the window loses its topmost status and is placed at the bottom of all other windows.
HWND_NOTOPMOST Places the window above all non-topmost windows (that is, behind all topmost windows). This flag has no effect if the window is already a non-topmost window.
HWND_TOP Places the window at the top of the Z order.
HWND_TOPMOST Places the window above all non-topmost windows. The window maintains its topmost position even when it is deactivated.
For more information about how this parameter is used, see the following Remarks section.
X
Specifies the new position of the left side of the window.
Y
Specifies the new position of the top of the window.
cx
Specifies the new width of the window, in pixels.
cy
Specifies the new height of the window, in pixels.
uFlags
Specifies the window sizing and positioning flags. This parameter can be a combination of the following values:
Value Meaning
SWP_DRAWFRAME Draws a frame (defined in the window's class description) around the window.
SWP_FRAMECHANGED Sends a WM_NCCALCSIZE message to the window, even if the window's size is not being changed. If this flag is not specified, WM_NCCALCSIZE is sent only when the window's size is being changed.
SWP_HIDEWINDOW Hides the window.
SWP_NOACTIVATE Does not activate the window. If this flag is not set, the window is activated and moved to the top of either the topmost or non-topmost group (depending on the setting of the hWndInsertAfter parameter).
SWP_NOCOPYBITS Discards the entire contents of the client area. If this flag is not specified, the valid contents of the client area are saved and copied back into the client area after the window is sized or repositioned.
SWP_NOMOVE Retains the current position (ignores the X and Y parameters).
SWP_NOOWNERZORDER Does not change the owner window's position in the Z order.
SWP_NOREDRAW Does not redraw changes. If this flag is set, no repainting of any kind occurs. This applies to the client area, the nonclient area (including the title bar and scroll bars), and any part of the parent window uncovered as a result of the window being moved. When this flag is set, the application must explicitly invalidate or redraw any parts of the window and parent window that need redrawing.
SWP_NOREPOSITION Same as the SWP_NOOWNERZORDER flag.
SWP_NOSENDCHANGING Prevents the window from receiving the WM_WINDOWPOSCHANGING message.
SWP_NOSIZE Retains the current size (ignores the cx and cy parameters).
SWP_NOZORDER Retains the current Z order (ignores the hWndInsertAfter parameter).
SWP_SHOWWINDOW Displays the window.
Return Values
If the function succeeds, the return value is nonzero.
If the function fails, the return value is zero. To get extended error information, call GetLastError.
Remarks
If the SWP_SHOWWINDOW or SWP_HIDEWINDOW flag is set, the window cannot be moved or sized.
All coordinates for child windows are client coordinates (relative to the upper-left corner of the parent window's client area).
A window can be made a topmost window either by setting the hWndInsertAfter parameter to HWND_TOPMOST and ensuring that the SWP_NOZORDER flag is not set, or by setting a window's position in the Z order so that it is above any existing topmost windows. When a non-topmost window is made topmost, its owned windows are also made topmost. Its owners, however, are not changed.
If neither the SWP_NOACTIVATE nor SWP_NOZORDER flag is specified (that is, when the application requests that a window be simultaneously activated and its position in the Z order changed), the value specified in hWndInsertAfter is used only in the following circumstances:
· Neither the HWND_TOPMOST nor HWND_NOTOPMOST flag is specified in hWndInsertAfter.
· The window identified by hWnd is not the active window.
An application cannot activate an inactive window without also bringing it to the top of the Z order. Applications can change an activated window's position in the Z order without restrictions, or it can activate a window and then move it to the top of the topmost or non-topmost windows.
If a topmost window is repositioned to the bottom (HWND_BOTTOM) of the Z order or after any non-topmost window, it is no longer topmost. When a topmost window is made non-topmost, its owners and its owned windows are also made non-topmost windows.
A non-topmost window can own a topmost window, but the reverse cannot occur. Any window (for example, a dialog box) owned by a topmost window is itself made a topmost window, to ensure that all owned windows stay above their owner.
If an application is not in the foreground, and should be in the foreground, it must call the SetForegroundWindow function.
Здесь тебя будут волновать флаги SWP_NOMOVE и SWP_NOSIZE, и hWndInsertAfter выставляеш с параметром HWND_BOTTOM.
