Cannot scroll LayoutControl content when mouse is over LayoutControlExpanderGroup content

[ClausDC]

I have a LayoutControl which contains LayoutControlExpanderGroup-Controls.

The LayoutControl's vertical space is set to a certain height but the content overflows that. As a result, a scrollbar is displayed - which is the desired behavior.

The problem is that when the mouse pointer is over the content of a LayoutControlExpanderGroup control, scrolling with the mouse wheel does not work anymore.

When the mouse pointer is over the header of a LayoutControlExpanderGroup, it works though.

I guess the Scrollviewer in the LayoutControlExpanderGroup control "steals" the mouse wheel event? Is there any way to fix that behavior?

[Martin Ivanov]

Hello Claus,

You are correct. The ScrollViewer inside the layout group control handles the mouse wheel, thus disabling the scrolling of the parent ScrollViewer. You can reproduce the same behavior if you wrap a ScrollViewer inside another ScrollViewer.

To achieve your requirement you can scroll the parent ScrollViewer manually on MouseWheel. Here is an example in code:

private void RadLayoutControl_PreviewMouseWheel(object sender, MouseWheelEventArgs e)
{
    var lc = (RadLayoutControl)sender;
    var sv = lc.FindChildByType<ScrollViewer>();
    double x = (double)e.Delta;
    double y = sv.VerticalOffset;
    sv.ScrollToVerticalOffset(y - x);
}

Regards,
Martin Ivanov
Progress Telerik