Add mousewheel support to riched20

[Hannu Valtonen]

Joris Huizer wrote:

 > Why not like
 >
 >  > +    SystemParametersInfoW(SPI_GETWHEELSCROLLLINES,0,
 > &pulScrollLines, 0);
 >  > +    gcWheelDelta = GET_WHEEL_DELTA_WPARAM(wParam);
 >  > +    if (gcWheelDelta >= WHEEL_DELTA && pulScrollLines)
 >  > +      nPos += pulScrollLines * (-gcWheelDelta / WHEEL_DELTA) * 8;
 >
 > just seems simpler;

It doesn't work quite that way. GET_WHEEL_DELTA_WPARAM() can return both 
positive and negative numbers so the abs() is still essential.

It's a question of taste whether to put it on to:

gcWheelDelta -= GET_WHEEL_DELTA_WPARAM(wParam);

or on to:

nPos += pulScrollLines * (-gcWheelDelta / WHEEL_DELTA) * 8;

Me, I like the first one but I don't really care one way or the other.

- Hannu Valtonen
Hannu.Valtonen at hut.fi