- Yes, just did it. If you need a repro project let me know.
- In the hud beginplay set input mode to UIOnly and create a widget and add it to the viewport. The widget should contain a button, the widget itself should fill the entire screen. Ensure that in the controller you set show cursor to true to show the mouse. Click on the button once to make it receive keyboard focus (to verify it does have focus you can use the focus render rule to always in interface under project settings). Afterwards click somewhere else in the window and you will notice it loses focus.
- I think instructions in 2. are enough, otherwise i will send the test project.