Edit control with transparent background scrolling issue

[ahal89]

I'm trying to make a EULA. So I have a multi line read-only edit control that the user needs to be able to scroll down on.

Additionally, since I'm using a custom skin for my main window background, the edit control background has to be transparent other wise it looks really ugly.

I simply used the WS_VSCROLL style to obtain the vertical scroll bar. The problem is that when I scroll down then up, the text doesn't refresh, i.e it draws on top of itself and creates garbage.

I've done some research, and I know that this is why:


case WM_CTLCOLORSTATIC: // Makes the static control backgrounds transparent
::SetBkMode((HDC)wParam, TRANSPARENT);
return (LRESULT)::GetStockObject(NULL_BRUSH); // Return NULL brush


What I don't know is how to fix it.
I've tried doing something like this:


case WM_SETTEXT: // Ensures that text is not drawn on top of previous text
if ( GetDlgCtrlID (hDlg) == EDIT_CONTROL_ID){
::InvalidateRect( hDlg, NULL, TRUE);
DefWindowProc(hDlg, WM_SETTEXT, 0, lParam);
}


This exact same code worked for a similar problem I had updating static text, but doesn't seem to work on the edit control (I'm guessing cause it doesn't fire a WM_SETTEXT on a scroll). I'm sure I have to intercept the EN_VSCROLL notification, but so far nothing I've tried has worked.

Any help is appreciated! (I'm also pretty new to win32 development)



EDIT: Ok, so I made some progress, but not much.. still need some help.


case WM_COMMAND: // COMMAND MESSAGE
wmId = LOWORD(wParam);
wmEvent = HIWORD(wParam);
// Parse the menu selections:
switch (wmId) {
case EDIT_ID:
if (wmEvent == EN_VSCROLL){
::ShowWindow (GetDlgItem(hDlg, wmId), SW_HIDE);
::SetDlgItemText (hDlg, wmId, g_eulaText);
::ShowWindow (GetDlgItem(hDlg, wmId), SW_SHOW);
::SetFocus(GetDlgItem(hDlg, wmId));
}
return TRUE;


then


case WM_SETTEXT: // Ensures that text is not drawn on top of previous text
if ( GetDlgCtrlID (hDlg) == EDIT_ID){
::InvalidateRect( hDlg, NULL, TRUE);
DefWindowProc(hDlg, WM_SETTEXT, 0, lParam);
}
break;


This has two major problems.

1. It turns the background into non-transparent (even though it still acts as a transparent background... see 2)
2. When I click and drag the scroll bar, it still draws on top of itself

Actually, just found out that EN_VSCROLL doesn't get sent when the user clicks on the actual scroll bar, which means that capturing EN_VSCROLL might not work... sigh