Then there is no bug at all. This option is disabled by default. To enable it:
- EDIT > Global Preferences
- Preferences > Special GUI Effects
- Enable the translucent workspace child windows option
- Click Apply Global or press F6
This option is disabled by default because in previous versions it caused problems on many Windows 8 installations, and in a few cases also on Windows 7. For sanity, I have decided to keep it disabled by default also in version 1.8.4. Turn it on and, if it doesn't give you screen rendering problems, keep it that way.