Question

I’m writing a small Windows application in Visual C++ without MVC. Its really small, it just contains one textfield, an OK-Button and an Cancel-Button.

The application is started by a background-process when user starts printing. When opening the application doesn’t get focus, isn’t even visible.

For the user it’s importend that the application is directly in focus, so they have as lease clicks as possible to use it.

I tried many many things to get the application in focus:

SetWindowPos(hWnd, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE);
SetForegroundWindow(hWnd);
ShowWindow(hWnd, SW_RESTORE);
SetFocus(hWnd);

I even repeated this calls in a timer. All of this doesn’t work. Now I found some remarks on MSDN:

The system restricts which processes can set the foreground window. A
process can set the foreground window only if one of the following
conditions is true:

The process is the foreground process.
The process was started by the foreground process.
The process received the last input event.
There is no foreground process.
The foreground process is being debugged.
The foreground is not locked (see LockSetForegroundWindow).
The foreground lock time-out has expired (see SPI_GETFOREGROUNDLOCKTIMEOUT in SystemParametersInfo).
No menus are active.

Anybody knows a workaround for this?

Answer 1

http://www.thescarms.com/vbasic/alttab.aspx seems to do the job

void forceToFront(HWND hWnd) {
HWND foregroundWindow = GetForegroundWindow();

if (foregroundWindow == hWnd) {
    // Window is already Foreground-window
    return;
}

if (SetForegroundWindow(hWnd)) {
    // could set window to foreground without any tricks
    return;
}

// attach thread of foreground-window to this window
DWORD foregroundThread = GetWindowThreadProcessId(foregroundWindow, NULL);
DWORD myThread = GetWindowThreadProcessId(hWnd, NULL);
AttachThreadInput(foregroundThread, myThread, true);
SetForegroundWindow(hWnd);
AttachThreadInput(foregroundThread, myThread, false);

}