Web browser widget not receiving some mouse input information

When using the web browser widget, it appears that some mouse input is ignored. In this example the handles that were working in previous versions of the engine are now ignored and do not receive input.

Regression: Yes (working in 4.17.2-3658906+++UE4+Release-4.17)

1. Download the attached project
2. Open the project
3. Play in editor
4. Once web browser is loaded click the button in the top left to run a java script
5. Try and click the white squares in each corner to resize the highlighted area

Result: The cursor changes to indicate that it can be used to resize, however when clicking the handles (white squares) the background is moved instead and the input to the handles is ignored
Expected: The input would go to the handles (white squares) and the highlighted area could be clicked and dragged to resize