Currently, in the Data Structure Properties Panel, when hovering over one of the available types from the Dropdown panel, each item contains an empty tooltip.
See attached image.

Repro Steps:

1) Create a new Studio Project containing a MainPage.xaml.
2) Navigate to the Data Panel and create a new Data Structure.
3) Add a new Data Property to the Data Structure created in Step 2).
4) Open the Data 'Type' dropdown for the Data Property created in Step 3).
5) Hover over any of the items in the dropdown menu.

Observe how a small off-white square appears under the hovered item.

Expected Results: If a Tooltip is displayed, it contains content.