Fix two bugs in SetScrollRange

[Dmitry Timoshkov]

"Troy Rollo" <wine at troy.rollo.name> wrote:

> This fixes two bugs in SetScrollRange:
> 
> 1. Setting the scroll range with the "bRedraw" flag set to true on a 
> non-control scrollbar results in the scrollbar being drawn over the whole 
> window area.
> 
> 2. If you don't set WS_HSCROLL/WS_VSCROLL on window creation, setting a scroll 
> range does nothing. Setting the scroll range to a non-zero range should cause 
> scroll bars to be displayed (and the appropriate flag to be set in the window 
> styles). Setting the range to a zero range should cause the relevant scroll 
> bar to be hidden (and the flag to be removed from the window styles).
> 
> The second attachment is a test program that can be used to verify the 
> behaviour associated with the second bug by using the left and right mouse 
> buttons to set a non-zero/zero scroll range on mouse-down/mouse-up. The left 
> mouse button affects SB_HORZ and the right affects SB_VERT.

Thanks Troy for fixing a breakage I introduced with my recent patch.
This patch certainly can be applied, after that I'll send a more
comprehensive test suite and a few more fixes I have in my tree.

-- 
Dmitry.