MFC VC++ CStatic only receiving WM_NCHITTEST

Question

I have created a small MFC Document View App in C++ and I am having some trouble receiving messages in a class that inherits from CStatic. I have managed to create the CStatic derivative and it is visible on my View however my message handlers are not being fired.

When using Spy++ it seems that window is only receiving WM_NCHITTEST and it is returning HTTRANSPARENT, which according to MSDN means:

"In a window currently covered by another window in the same thread (the message will be sent to underlying windows in the same thread until one of them returns a code that is not HTTRANSPARENT)."

Here is an exert from Spy++:

<000001> 001D1350 S WM_NCHITTEST xPos:128 yPos:167
<000002> 001D1350 R WM_NCHITTEST nHittest:HTTRANSPARENT
<000003> 001D1350 S WM_NCHITTEST xPos:128 yPos:166
<000004> 001D1350 R WM_NCHITTEST nHittest:HTTRANSPARENT
<000005> 001D1350 S WM_NCHITTEST xPos:128 yPos:165
<000006> 001D1350 R WM_NCHITTEST nHittest:HTTRANSPARENT
<000007> 001D1350 S WM_NCHITTEST xPos:128 yPos:164
<000008> 001D1350 R WM_NCHITTEST nHittest:HTTRANSPARENT

This seems strange because the CStatic derivative is the only child window of my view. I created it like this:

Create(pItem->Value->GetBuffer(), WS_CHILD | WS_VISIBLE | SS_CENTER, Rect, Parent);
ShowWindow(SW_SHOW);

where Parent is a pointer to the CView.

Any help would be really appreciated.

EDIT:

Foo.h

class Foo: public CStatic
{
    DECLARE_DYNAMIC(Foo)
public:
    Foo();
    virtual ~Foo();
    virtual void CreateCtrl(CWnd * Parent, POINT TopLeft, SIZE sz);

protected:
    DECLARE_MESSAGE_MAP()
public:
    afx_msg void OnLButtonUp(UINT nFlags, CPoint point);
};

Foo.cpp

void Foo::CreateCtrl(CWnd * Parent, POINT TopLeft, SIZE sz)
{
    CRect Rect(TopLeft, sz);
    Create(pItem->Value->GetBuffer(), WS_CHILD | WS_VISIBLE | SS_CENTER, Rect, Parent);
    ShowWindow(SW_SHOW);
}

BEGIN_MESSAGE_MAP(Foo, CStatic)     
    ON_WM_LBUTTONUP()
END_MESSAGE_MAP()

void Foo::OnLButtonUp(UINT nFlags, CPoint point)
{   
    AfxMessageBox("Hello World!");
    __super::OnLButtonUp(nFlags, point);
}

What message handlers are not being fired? Have you searched SO with CStatic? — Edward Clements
The main one is OnLButtonUp. I did have a look around SO and though some questions are similar I don't think they are the same as mine. — Shane Haw
can you post some code of how you are declaring your CStatic derived class and your OnLButtonUp handler? — Edward Clements

Igor Tandetnik Igor Tandetnik · Accepted Answer · 2013-08-12T16:31:28

See Microsoft's article "About Static Controls", and in particular this part:

WM_NCHITTEST: Returns HTCLIENT if the control style is SS_NOTIFY; otherwise, returns HTTRANSPARENT.

Once the window returns HTTRANSPARENT from WM_NCHITTEST, all further mouse messages go to the window underneath it in Z-order; in your case, the parent view. The window is "transparent" as far as mouse handling is concerned.

MFC VC++ CStatic only receiving WM_NCHITTEST

2 Answers