Help with this issue

Question

Here is the problem:

The way the GUI system I'm using works is as follows:

A widget can listen to mouse events. The listeners can consume an event they are listening to and as a result, the widget they were listening to will not receive the event, even if it was intended for them, only the listener will have received it.

The problem comes in here:

A scrollpane has a ListBox inside. The listbox can be scrolled. The Scrollpane can also be scrolled. What happens right now is when I mousewheel and the widget under the mouse is the listbox, both the listbox and the scrollpane move. The only solution I see is that the scrollpane consumes all mousewheel events, but then there is no way for the ListBox to ever be scrolled.

The behavior I desire is for the ListBox to scroll when it has focus, but if I did this, it would not work because for example if a radio button inside the scrollpane is focused, I still want the scrollpane to scroll, it is only for widgets with scrollbars such as textbox and listbox where this is not desired.

Thanks

Also, the gui system I'm using is my own which I'm developing.

Answer 1

The usual way to deal with this is that the ListBox only consumes the event if it actually scrolls . If you place the mouse in the listbox and use the scrollwheel the listbox scrolls until it reaches its scroll limit. After that further moves of the wheel cause the scrollpane to scroll.

Obviously there are variants on that - the important thing is to decide what you actually want to happen.

You also need another way of scrolling the scrollpane, so that if the user explicitly wants to scroll it they can, without having to scroll to the end of the ListBox. Scrollbars on the ScrollPane would be one way. You should also make sure there is a way of scrolling the ListBox without using the mouse wheel.