Re: Capturing scrolling of Delphi TListbox

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Posted by webmaster Guido on March 11, 2004 at 15:30:09:

In Reply to: Capturing scrolling of Delphi TListbox posted by Joey on March 07, 2004 at 22:45:19:

: with Delphi TListBox... how can i see if the user has scrolled??? at the moment i have a timer set to check the TopIndex and if it differs to the previously set one it fires the event... but is there a proper way of doin it??


There is no OnScroll event for Delphi's TListbox, nor its ancestor TCustomListbox. That's because its vertical scrollbar is handled directly by Windows (not by Delphi's VCL code).

You can't derive a custom component from TListbox or TCustomListbox with an OnScroll property. If you want such a component, I'm afraid you'll have to write it from scratch.

(Note: there are only two components with scrollbars that you can control yourself: TForm and TScrollBox.)

So, is it the "proper way" how you handle things? If it works, it's OK :) -- anyway it's easier than writing a complete new TJoeyScrollbox ;-)

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