[Lazarus] Issue #15866: TIpHtmlPanel scrollbar not functional on Win64

Gerd Sager gsa at bg-gs.de
Tue Jun 18 20:06:15 CEST 2013


Am 18.06.2013 13:53, schrieb Juha Manninen:
>
> http://bugs.freepascal.org/view.php?id=15866
>
> Gerd Sager and Zeljan:
> It is good to have some kind of fix for the issue, but IMO the problem
> is elsewhere.
> In my understanding the LM_xxx messages should map to WM_xxx messages
> on Windows. The idea is to simulate the Windows message system in a
> cross-platform way.
> Thus, the problem is in wrong mapping of those messages somewhere.
>
> Regards,
> Juha

Hi Juha,

scrolling works well anywhere in the LCL, except in the iphtml package
on 64 bit windows.
The reason is that the field ScrollCode of the TWMScroll record always
contains 0 (windows 64 bit).
Due to a change in the size of lparam and wparam in windows 64 bit the
TWMScroll record - defined in FPC's messages.inc - does no longer fit.

You will find the correct definition in the TLMScroll record in the
LCL LMessages unit. The LCL itself uses the TLMScroll record and the
messages LM_HSCROLL and LM_VSCROLL as you can see in TCustomScrollBar
(stdctrls.pp).

Kind regards

Gerd




More information about the Lazarus mailing list