Drawing line on PDF - not working in Acro 8 and 9

Question

I have code in a simple Acrobat plugin that draws a line from the point where the mouse button was pressed to the current mouse pointer position, refreshing the lines position as long as the mouse button is being held down. The code works fine in Acrobat 6 and 7, but appears to do nothing in Acrobat 8 and 9 (the code is being called, but no line is drawn). Any insights would be most appreciated. The code is copied below - the first function simply converts the User space point to windows screen coordinates, and the clickProc function is called by an AVAppRegisterForPageViewClicks notification.
Thanks in advance!
void AVPageViewUserPointToScreen(AVPageView pageView, ASFixedPoint *src, POINT *dest)
ASFixedMatrix matrix;
ASFixedPoint fp;
AVPageViewGetPageToDevMatrix(pageView, &matrix);
ASFixedMatrixTransform(&fp, &matrix, src);
dest->x = FixedTruncToInt16(fp.h);
dest->y = FixedTruncToInt16(fp.v);
ACCB1 ASBool ACCB2 clickProc(AVPageView pageView, AVDevCoord x, AVDevCoord y, AVFlagBits16 flags, AVTCount clickNo, void *data)
ASFixedPoint fpStart, fpEnd;
POINT drawStart, drawEnd;
AVDevCoord x0, y0;
WinPort winPort;
LOGPEN pen;
POINT width;
//store the start point in user space
AVPageViewDevicePointToPage(pageView, x, y, &fpStart);
//Get the starting point in screen coordinates
AVPageViewUserPointToScreen(pageView, &fpStart, &drawStart);
drawEnd.x = drawStart.x;
drawEnd.y = drawStart.y;
winPort = (WinPort)AVPageViewAcquireMachinePort(pageView);
pen.lopnStyle = PS_SOLID;
pen.lopnColor = RGB(128, 128, 128);
width.x = 1;
pen.lopnWidth = width;
HPEN hPen = CreatePenIndirect(&pen);
SelectObject(winPort->hDC, hPen);
SetROP2(winPort->hDC, R2_NOT);
while (AVSysMouseIsStillDown())
AVPageViewGetMousePosition(pageView, &x0, &y0);
//erase the previous line
MoveToEx(winPort->hDC, drawStart.x, drawStart.y, NULL);
LineTo(winPort->hDC, drawEnd.x, drawEnd.y);
//store the new end point in user coordinates
AVPageViewDevicePointToPage(pageView, x0, y0, &fpEnd);
//Get the new end point in screen coordinates
AVPageViewUserPointToScreen(pageView, &fpEnd, &drawEnd);
//draw the NEW line
MoveToEx(winPort->hDC, drawStart.x, drawStart.y, NULL);
LineTo(winPort->hDC, drawEnd.x, drawEnd.y);
return TRUE;

Answer 1

Hmm...
I don't see anything obvious that would have changed in Acrobat 8 and later. We did change from 16->32 bit coordinates back in Acrobat 7 - but you say the code works fine there, yes?
If you are still having problems, I would recommend filing a formal support request with developer support.