Disabling All Top Level Thread Windows

class DisableTaskWindows
{
public:
 DisableTaskWindows()
  { ::EnumWindows(EnumWindowsProc, FALSE); }
 ~DisableTaskWindows()
  { ::EnumWindows(EnumWindowsProc, TRUE); }

private:
 static BOOL CALLBACK EnumWindowsProc(HWND hwnd, LPARAM lParam);
};

BOOL CALLBACK DisableTaskWindows::EnumWindowsProc(HWND hwnd, LPARAM lParam)
{
 if (::GetWindowThreadProcessId(hwnd, NULL) == ::GetCurrentThreadId())
  ::EnableWindow(hwnd, lParam);
 return TRUE;
}

It becomes a little more complicated if you need to specify the thread ID:

class DisableTaskWindows
{
public:
 DisableTaskWindows(DWORD dwThreadID);
 ~DisableTaskWindows();

private:
 static BOOL CALLBACK EnumWindowsProc(HWND hwnd, LPARAM lParam);

 BOOL m_bEnable;
 DWORD m_dwThreadID;
};

BOOL CALLBACK DisableTaskWindows::EnumWindowsProc(HWND hwnd, LPARAM lParam)
{
 if (::GetWindowThreadProcessId(hwnd, NULL) == ((DisableTaskWindows*)lParam)->m_dwThreadID)
  ::EnableWindow(hwnd, ((DisableTaskWindows*)lParam)->m_bEnable);
 return TRUE;
}

DisableTaskWindows::DisableTaskWindows(DWORD dwThreadID)
 : m_dwThreadID(dwThreadID)
{
 m_bEnable = FALSE;
 ::EnumWindows(EnumWindowsProc, (LPARAM)this);
}

DisableTaskWindows::~DisableTaskWindows()
{
 m_bEnable = TRUE;
 ::EnumWindows(EnumWindowsProc, (LPARAM)this);
}

It's very simple to use:

CMyDialog dlg;
{
 DisableTaskWindows dtw;
 - or -
 DisableTaskWindows dtw(AfxGetThread()->m_nThreadID);
 dlg.DoModal();
} // Destroys dtw which re-enables the windows

You could also create a class derived from CDialog, override DoModal and add a DisableTaskWindows object before calling the base class. This would make it even more seemless:

class CDisablingDialog : public CDialog
{
public:
 CDisablingDialog(LPCTSTR lpszTemplateName, CWnd* pParentWnd = NULL)
  : CDialog(lpszTemplateName, pParentWnd) {}

 CDisablingDialog(UINT nIDTemplate, CWnd* pParentWnd = NULL)
  : CDialog(nIDTemplate, pParentWnd) {}

 virtual int DoModal()
 {
  DisableTaskWindows dtw;
  return CDialog::DoModal();
 }
};

There are lot's of combinations you could come up with, but I'll leave that as an excercise for the reader.

Date Last Updated: April 24, 1999