On setting Anchor Preset in 'Rect Transform' Anchor Preset window remains active even after setting Preset. Anchor Preset window needs to close manually every time by shifting mouse focus to elsewhere.

Reproduction steps:
1. Create a new project.
2. Hierarchy > UI > Select any UI objects > For ex: Panel
3. Click Canvas -> Panel
4. Change Anchor Preset and observe the Anchor Preset window.

Actual result:
Anchor Preset window remains active even after setting Anchor Preset.

Expected result:
Anchor Preset window should have to close once respective preset is set by multi-clicking.

Occurring on: 2021.1.0b1, 2020.2.1f1, 2020.1.17f1, 2019.4.16f1, 2018.4.30f1

Environment: Windows 10 and Mac 10.15