Auto-scroll pause while view receives new messages based on Rich Edit View

[Jinyup]

Dear all,

First of all, I am stuck in vertical auto-scroll pause during receiving new messages.
This is already applied to commercial messengers, Visual C++ debugging window, etc.

When user clicks left button in those window, the vertical scroll is stopped but messages are stack up continuously.
This is needed to my project as attached.

The attached project is made with SDI and rich edit view.
In main view, I would like to add new process module for thest purposes in OnLButtonUp().
In this function, ES_AUTOVSCROL is removed to remove auto-scroll but this window style is newly set afterwards as follows..

dwStyle = GetWindowLong(m_hWnd, GWL_STYLE);
// Changes an attribute of the specified window for style change.
dwStyle &= ~ES_AUTOVSCROLL;
dwStyle = SetWindowLong(m_hWnd, GWL_STYLE, dwStyle);

Please give me your valuable tips and solutions.

Thanks and regards,
Jay