How to reproduce:
1. Create a new project
2. Install and set up Bolt
3. In the Project create a new Bolt Flow Macro and edit the graph
4. In the Flow Graph window right-click in the grid area to open the context menu
5. Notice the behavior of the menu when mousing over different entries

Expected result: The menu doesn't flicker while being moused over and no errors show up in the Console
Actual result: The menu flickers and throws "ArgumentException: Getting control 1's position in a group with only 1 controls when doing mouseMove" errors in the Console

Reproducible with: 2019.4.29f1, 2020.3.14f1
Not reproducible on: 2018.4.35f1, 2021.1.13f1, 2021.2.0b3, 2022.1.0a1

Notes:
1. Reproducible on Ubuntu 18.04
2. Not reproducible on Windows 7
3. Regression is not present on any trunk version, only on 2019.4 and 2020.3 LTS