[Lazarus] OnMouseWheel event issue

And3mD and3md at gmail.com
Fri Nov 19 20:49:06 CET 2010


Some time ago I have the same problem.
Unfortunately this is windows design.

When you scroll then:
If focused control supports scrolling its get WM_MOUSEWHELL message, if it  
not support scrolling message is send to focused control parent.

To handle this message in Lazarus you must use SetWindowLong or  
SetWindowLongPtr something like this:


Andrzej Kilijanski

Dnia 19-11-2010 o 10:03:58 Birger Jansen <birger at cnoc.nl> napisaƂ(a):

> Hi all,
> I have a TPanel on a TForm and an event on the TForm.OnMouseWheel. This  
> works when I use the mousewheel on the form. But as soon as the cursor  
> is over the TPanel, the OnMouseWheel event on the parent form is not  
> triggered. Since the TPanel has no OnMouseWheel there is no way to use a  
> mousewheel on a panel.
> In Delphi, the TPanel passes the event to the parent control (TForm).
> Shall I report a bug or is this designed behaviour?
> I think it relates to this: http://bugs.freepascal.org/view.php?id=12361
> Kind regards,
>   Birger Jansen
> --
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