Visual C++ :: CStatic Control Flicker Only When Running With Windows Classic Theme

I have a C++/MFC application that displays a count in a window:

The count (text) is displayed via a `CStatic` control. The mechanism is very simple. I call it every 1000 ms and update the text as such:

Code:
void CTestCountdownFlickerDlg::RedrawCounter(LPCTSTR pText)
{
CStatic* pTxtBox = (CStatic*)this->GetDlgItem(IDC_STATIC_COUNTER);
ASSERT(pTxtBox);

[Code]....

What happens is that the `CStatic` control updates without any issues on the OS with visual themes enabled, but if I run it on the OS with the Windows Classic theme (for instance, the screenshot above is from Windows 7) the `CStatic` control produces a visible flicker every time it updates the text.

Well, I understand that I'm nitpicking here, still I would really like to get rid of this flicker.

Here's what I tried:

1. In my actual project I tried subclassing the `CStatic` control and removed the processing of `WM_ERASEBACKGROUND` by simply returning 1. That didn't work.

2. In the same subclass for `CStatic` control I tried to override `WM_PAINT`, but that didn't work at all. So I'm not sure if I'm going too far with it at this point.

I'm attaching the C++/MFC source code for my test project .....