Pointer events in Control vs. Panel.

[sonicsmooth]

I want to capture the mouse movement in a custom control for dragging, etc., so I derive from Control since no Children.
When I don't draw anything in Render, there are no mouse movements captured.
The only way I get mouse events is when the mouse goes over something that has been drawn in Render, such as individual lines (I get quick little PointerEnter and PointerLeave events when mouse crosses a line) or shapes, and I don't get any click events unless I'm over a drawn pixel somewhere.

I can draw a large rectangle to capture the mouse, or alternately derive from Panel and define a (possibly transparent) Background in .xaml, which seems to have the same effect as me just drawing a rectangle.

Is this expected? Is there any way to get mouse events from a completely blank Control?

My current solution is to derive from Panel (even though I [currently] don't have any Children here), and then specify a blank background.

public partial class GraphGrid : Control /* or Panel */
{
    // Control does not have Background Property 
    // Panel does have Background Property

    public GraphGrid()
    {
        InitializeComponent();
        this.PointerMoved += (o, e) => Console.WriteLine("Moved");
        this.PointerEnter += (o, e) => Console.WriteLine("Enter");
        this.PointerLeave += (o, e) => Console.WriteLine("Leave");
        this.PointerPressed += (o, e) => Console.WriteLine("Pressed");
        this.PointerReleased += (o, e) => Console.WriteLine("Release");
    }

    public override void Render(DrawingContext context)
    {
        // Avalonia draws background for me if deriving from Panel
        // and if Background specified in xaml.

        // No Background property to draw if deriving from Control

        // I only get mouse events over stuff that has been drawn,
        // ie a Background or custom graphics.
        // I don't get mouse events on a completely clear/blank Control
        // or Panel.
    
        base.Render(context);

        // Draw custom graphics
        context.DrawBlaBla(...);

    }
}

[timunie]

You need any kind of Background for hit testing to work. Transparent is fine, but null will not work. For Panel, null is default.

[sonicsmooth]

Thanks, I figured this is by design. I'm just using a Panel with defined background.