There’s a small incompatibility in Beryl which causes certain program windows to appear translucent or transparent.
A simple fix for this is to
- Open up the Beryl Settings manager
- Click Windows Management
- Enable and select the WIndow Specific Settings option
- Under the Rules tab, expand Disable ARGB Visual, and click Add (the + button).
- Select Class Name in the list, click Grab and click on the window that is causing problems.
- Click ‘OK’
You should see something appear in the Disable ARGB Visual list like
In this case, I was having trouble with the terminal server client programs running in more than 256 colours.
You may need to reload Beryl for this to apply properly.