Drop hint IDropInfoBuilder is used renders incorrect VisualTarget

[bsundsbo]

Describe the bug
I need to support drop of element on ComboBox, as well as drop hint. When the combobox has IsEditable=true, the internal TextBox for does not allow drop, and drop hint does not render on the control.

The workaround for allowing drop on the internal TextBox is to create a XAML behavior, and assign IDropInfoBuilder to the TextBox to create a IDropInfo with the ComboBox as the sender.

The workaround does it's job to allow the drop, though the drop hint does not display when the cursor is over the internal TextBox.

Expected behavior
Expecting drop hint to display when cursor is over the textbox of the combobox

Screenshots

Desktop (please complete the following information):

• OS: Windows 11, .NET Core 9
• Version 4.0.0

Additional context
Working on fork to address issue

[bsundsbo]

Created PR to address this issue

I've also provided ComboBoxDropBehavior and ComboBoxDropInfoBuilder to demonstrate. ComboBoxDropInfoBuilder might be relevant to include in the projec

Updated Sample app. It works as expected currently, but easy to reproduce by undoing changes to DragDrop.cs and DropHintHandler