Re: Strange behaviour of scrollbars on MacOSX

[Steven Tamm <steventamm@mac.com>]

The scrollbar thumb code is the most tetchy of the gui code.  It is 
trying to emulate the "Mac" way of doing things by modifications to the 
NT scroll-bar code.  But it is very difficult to handle the thumb 
correctly.  This is because Carbon "wants" you to use 
TrackMousePosition and block waiting for a change in the mouse.  
Instead we are doing the thumb handling by hand.

For example, it responds differently to a "hold" on the thumb vs. a 
"click" on the thumb.  Try it and you'll see.  There's a bug there 
someplace, and I would suspect it's someplace in 
x_scroll_bar_report_motion.   I couldn't get a real stack trace for the 
call to report_motion (from XTmouse_position)

I can't debug this just now; if anyone can help it would be much 
appreciated.

-Steven

On May 2, 2004, at 4:32 AM, Piet van Oostrum wrote:

> With CVS Carbon Emacs on MacOSX the scrollbars behave quite strangely
> compared to other MacOSX applications, and I would say, probably 
> strange
> compared to other OSs.
>
> In another application when you click on the blue slider in the 
> scrollbar
> and don't move the mouse, everything stays as it was, no scrolling 
> takes
> place. On MacOSX, however, when you do this, either the scrollbar 
> changes
> position (just when you click on it) or the scrollbar stays put but the
> text scrolls. Sometimes it is possible to scroll through your buffer
> (probably with gaps) with repeatedly clicking on the same location in 
> the
> slider without moving the mouse. Sometimes it goes back and forth. I 
> know
> that emacs has different ideas about scrollbars but is there a way to 
> get
> the same behaviour as other apps?
> -- 
> Piet van Oostrum <piet@cs.uu.nl>
> URL: http://www.cs.uu.nl/~piet [PGP]
> Private email: P.van.Oostrum@hccnet.nl
>
>
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