Steps to repro:

1. Open attached project and 't1' scene;
2. Open 'Light Explorer' window (Window>Lighting>Light Explorer);
3. Select any of the Intensity fields in the Light Explorer window;
4. Click on any place in the field and observe that the whole field is highlighted;
5. Click again on the certain place in the field, trying to put the cursor there.

Expected result:
The cursor is set to the certain place in the field.

Actual result:
The whole field is highlighted. There is no way to set the cursor to the certain place in the field. See attached video.

Notes:
- Reproducible in 2018.1.0b1, 2017.3.0f3, 2017.2.1p1;
- Reproducible on Windows 10 and macOSX 10.13.1.