On dragging the mouse cursor over the input field of "Margins(Left, Top, Right, Bottom)" properties don't change its value under "Extra Settings" from TextMeshPro - Text (UI) in the Inspector, refer the attached video.

Steps to repro:
1. Create a new project.
2. Window > Package Manager > TextMeshPro(3.0.0-Preview.13) > Install
3. Hierarchy > Create > 3D Objects > Text - TextMeshPro
4. Insepcto > TextMeshPro-Text(UI) > Extra Settings > Margins
5. Change the value of Margins (Left, Top, Right, Bottom) using mouse dragger

Actual Result:
Input value for the Margins(Left, Top, Right, Bottom) is not changing on dragging the mouse over it

Expected Result:
Input value for the Margins(Left, Top, Right, Bottom) is change using mouse dragger

Occurring on:
2020.2.0a14, 2020.1.0b12, 2020.1.0a1 with package version 3.0.0-preview.13, 2.1.0, 2.1.0-preview.1

Working fine in:
2020.1.0a1, 2019.3.15f1 with package version 2.0.1, 1.4.1

Environment:
Windows10 and macOS 10.14