How to reproduce:
1. Open attached project "Bolt1FlowMachine_stripped2.zip"
2. In Project window, select "New Flow Macro"
3. In Inspector window, click on "Edit Graph"
4. In "Flow Graph" window, right-click anywhere
5. Left-click in "Flow Graph", outside the popup panel (in order to cancel the right-click panel)

Expected result: the panel disappears
{panel}
 {panel}

Actual result: the panel does not disappear, right-clicking again results in an error

Reproducible with: 2020.1.0a22, 2020.1.0b9, 2020.2.0a11 (Bolt 1.4.12) (thrown error "InvalidOperationException: Cannot open two instances of the fuzzy window at once.")

Not reproducible with: 2018.4.23f1, 2019.3.14f1, 2020.1.0a21 (Bolt 1.4.12)

Could not test with: 2020.1.0a1, 2020.1.0a20 ("TypeLoadException: Could not load type 'UnityEditor.Progress' from assembly 'UnityEditor, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'.")