How determine if mouse points to maximise button of window under cursor

Question

How determine if mouse points to(hover on) maximise button of window even if this window is not of my application. Is there API for that ?

[GetTitleBarInfo](http://msdn.microsoft.com/en-us/library/windows/desktop/ms633513(v=vs.85).aspx) looks very promising. — Raymond Chen, Feb 01 '12 at 21:18
@Raymond, that API appears to only tell whether the button is *visible* or *pressed*, but not whether the mouse is merely *hovering* over the button. — Rob Kennedy, Feb 01 '12 at 22:38
valdo's got your answer, but this sounds suspiciously like an [XY problem](http://meta.stackexchange.com/questions/66377/what-is-the-xy-problem) to me. I'm sure there's a better way than the proposed solution you've invented. — Cody Gray - on strike, Feb 02 '12 at 04:30
@RobKennedy It also gives you the coordinates of the button, which you can use to determine whether the mouse is in it. — Raymond Chen, Feb 02 '12 at 05:45
Where, @Raymond? `TITLEBARINFO` has the coordinates of the whole title bar, plus an array for the states of the buttons. I don't see an array of coordinates or any way to tell the API which button you're interested in the coordinates of. — Rob Kennedy, Feb 02 '12 at 14:47
@RobKennedy Oops, you're right. I had it confused with the other accessibility interface `IAccessible`, which has a `get_accLocation` method. — Raymond Chen, Feb 02 '12 at 18:21

score 5 · Accepted Answer · answered Feb 01 '12 at 20:43

You may send a WM_NCHITTEST to that window. The return value will correspond to the object type on the requested coordinates.

Something like this:

bool IsMouseOverMaxBtn(HWND hWnd)
{
    POINT pt;
    VERIFY(GetCursorPos(&pt)); // get mouse position

    int retVal = SendMessage(hWnd, WM_NCHITTEST, 0, MAKELONG(pt.x, pt.y));

    return HTMAXBUTTON == retVal;
}

Edit:

You may send this message to any window (not necessarily belong to your thread/process). Since no pointers are involved (such as string pointers) - there's no problem.

However you should note that sending (not posting) a message to a window belonging to another thread is a pretty heavy operation, during which your thread is suspended. There may even happen a situation where your thread hangs, because the thread of the application that serves that window hangs.

You may consider using SendMessageTimeout to guarantee your thread won't hang.

How determine if mouse points to maximise button of window under cursor

1 Answers1