[news.eclipse.platform.swt] Re: Controls on ScrolledComposite 'guzzles'

[Adam Pordzik <adresseverbummelt@xxxxxx>]

Veronika Irvine schrieb:

> For me, the mouse wheel events go to the widget with focus (not the widget 
> my cursor is over).  If the widget with focus does not make use of the mouse 
> wheel events, the events are propogated up the parent heirarchy until a 
> widget does make use of them.

I've added a display.addFilter (SWT.MouseWheel, ...) to see what will 
happen and remarked that some rotations doesn't produced any event, 
although the inner Composite was beeing scrolled.

> The problem with Labels is that they do not take focus. As a result,
> another widget such as a button which does take focus will be getting the 
> mouse wheel events and the events will be going to the parent hierarchy of 
> the button rather than the label.

What I don't understand, is why does wheel-scrolling still works with 
the "malicious" Control focussed, as long my mouse is over Composite or 
scrollableComposite, although they do not have focus?

> One workaround is to use Text with the style READ_ONLY instead of a Label. 
> The Text widget can take focus.

...and keeps it because Text is also scrollable. How do I can send an 
Event to the parent manually, or tell Text to ignore the event? I'd 
assumed "setCapture(false)" for this job, but...

I am still nearly as confused as at the beginning. :-/

For now I've worked aroud with an display.addFilter, and look whether 
mouse is over my scrollableComposite:

display.addFilter(SWT.MouseMove, new Listener () {
    public void handleEvent(Event e) {
        Control p = (Control) e.widget;
        while (p != null) {
            if (p == scrollableComposite) {
                p.setFocus();
                break;
            }
            p = p.getParent();
        }
    }
});

This works satisfying, but I'm not sure whether this is a good approach.

A

P.S.

Veronika, as I see, you are the owner of this what I've commited as a 
bug. If you like, I can send you a more illustating example.

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