The geometry window’s feature tree has disappeared or fills the entire workspace / Feature tree disappeared or fills the entire screen

If the feature tree section is narrowed so much that it disappears completely, you can no longer access it with the mouse.
The opposite can also happen — the tree is so wide that the geometry is not visible at all.
Restore it as follows:

1. Open File → This Software Version → open the user folder from the bottom of the dialog.

2. Close G4.

3. Open the text file windows.xy with Notepad.

4. Delete the two rows starting with EC:embedded_container... (these rows are near the end of the file, see image above).

5. Save windows.xy.

6. Restart G4.