I have a rich edit control, but in certain cases I need to resize it.

Basically, it comes down to this. I know the contents of the control. I know the width. Given those, I need to calculate the height.

I've played with all kinds of variations of EN_REQUESTRESIZE, but no matter the width of the window I pass in, it doesn't recalculate the height properly (I even deliberately set the window height to something ridiculous (5) to force a recalculation of the height of the REQRESIZE fuction, but it always comes back with the same values in rc->top and rc->bottom (0 and 825 to be exact)), so I think I need to do a more manual recalculation of the height of the window.

It seems like this should be something you ought to be able to do, but there doesn't seem to be an obvious way to do it.

Here is the code I am using:

        case WM_NOTIFY:
            {
            ostringstream ss;
            if (wParam == TTW_TOOLTIPTEXT)
                {
                if (((NMHDR*)lParam)->code == EN_REQUESTRESIZE)
                    {
                    GetWindowRect(ConfiningWindow, &ConfiningRect);
                    ReqResize = (REQRESIZE*)lParam;
                    GetCursorPos(&CursorPoint);
                    X = CursorPoint.x + 10;
                    Y = CursorPoint.y + 10;
                    //don't fall off the bottom of the confining window
                    if (Y + (ReqResize->rc.bottom - ReqResize->rc.top) +15 > ConfiningRect.bottom)
                        Y = ConfiningRect.bottom - (ReqResize->rc.bottom - ReqResize->rc.top) - 15;
                    //also, don't go past the right side of the main window
                    if (X + (ReqResize->rc.right - ReqResize->rc.left) +15 > ConfiningRect.right)
                        X = CursorPoint.x - (ReqResize->rc.right - ReqResize->rc.left) - 15;
                    //at this point we should be entirely inside the window, unless the text is so large the tooltip is higher than the entire window itself.
                    if (Y < ConfiningRect.top)
                        {
                        ss << "Retry: X,Y: " << X << "," << Y << "    ReqResize: " << ReqResize->rc.left << "," << ReqResize->rc.right << "," << ReqResize->rc.top << "," << ReqResize->rc.bottom << "    Confining: " << ConfiningRect.left << "," << ConfiningRect.right << "," << ConfiningRect.top << "," << ConfiningRect.bottom << "\r\n";
                        OutputDebugString(ss.str().c_str());
                        ReqResize->rc.right += 50;
                        SetWindowPos(ToolTipWindow, HWND_TOPMOST, X, Y, ReqResize->rc.right - ReqResize->rc.left+8, ReqResize->rc.bottom - ReqResize->rc.top+8, SWP_HIDEWINDOW);
                        SetWindowPos(ToolTipText, HWND_TOP, 0, 0, ReqResize->rc.right - ReqResize->rc.left, ReqResize->rc.bottom - ReqResize->rc.top, SWP_HIDEWINDOW);
                        SendMessage(ReqResize->nmhdr.hwndFrom, EM_REQUESTRESIZE, 0, 0);
                        return 0;
                        }  
                    SetWindowPos(ToolTipWindow, HWND_TOPMOST, X, Y, ReqResize->rc.right - ReqResize->rc.left+8, ReqResize->rc.bottom - ReqResize->rc.top+8, SWP_SHOWWINDOW);
                    SetWindowPos(ToolTipText, HWND_TOP, 0, 0, ReqResize->rc.right - ReqResize->rc.left, ReqResize->rc.bottom - ReqResize->rc.top, SWP_SHOWWINDOW);
                    return 0;
                    }
                return 0;
                }
            return 0;
            }
 

So, just to clarify, that ODS string gives values like such:

Retry: X,Y: 1015,30 ReqResize: 0,200,0,825 Confining: 460,1460,330,870
Retry: X,Y: 1015,30 ReqResize: 0,250,0,825 Confining: 460,1460,330,870
Retry: X,Y: 1015,30 ReqResize: 0,300,0,825 Confining: 460,1460,330,870

Notice ReqResize width is increasing by 50 at a time, but the height isn't changing.

Any suggestions?

Maybe you could check for the vertical scroolbar range value, and if it's higher than the height of you're richedit box, change it to this value.