AutoCompleteBox - Popup does not open if Textbox is not Focused

[juicebyjustin]

I cannot get the popup to open until after I have the textbox in focus. This happens when any text is in the textbox. If the textbox is empty then the textbox does not have to be in focus to open the popup. This is reproducible in the sample on Github. I have tried to navigate the code in order to create a pull request but it is over my head.

UpdateVisualState in AutoCompleteBox.cs is being called with IsDropDownOpen = true but the popup does not open.

How to reproduce:

1. Navigate to tab 'AutoCompleteComboBox'
2. Select an item in the Type: AutoCompleteComboBox
3. Navigate to any other tab
4. Navigate back to tab 'AutoCompleteComboBox'
5. Click the down arrow which should open the popup box.

[jogibear9988]

I also tried to fix... It's not easy, until now I'm out of luck