SyntaxVisualizer contents disappears from time the editor is focused until an edit has been made

[dpoeschl]

Version Used: 16.1 P1. No repro on 16.0

1. Open the syntax visualizer, and get it working (might require typing something in the editor)
2. Click somewhere outside the text editor to remove focus (Solution Explorer works, but so does the Syntax Visualizer itself)
3. Click back inside the text editor

Expected: Syntax Visualizer keeps working Actual: Syntax Visualizer treeview disappears until an edit is made to the open document

[dpoeschl]

Tag @jmarolf