Steps to reproduce:

1. Create a Unity project
2. Click the "AI" button
3. Click "Agree and install Unity AI"
4. Go to AI > Generate New > Cubemap
5. Type in anything into the Prompt (e.g. Sky)
6. While still in the Prompt field, click "Enter" on the keyboard and hold until ~80 lines are created
7. Click Generate
8. Once generated, hover over the generated image thumbnail
9. Observe the tooltip

Actual results: Tooltip height scales with the number of empty lines and stretches vertically across most or all of the Editor window, showing a large empty area and obstructing the view

Expected results: Tooltip has a reasonable maximum size, ignores or collapses empty lines, and truncates very long prompts so it stays compact and readable

Reproducible with versions: 1.6.0-pre.1, 2.0.0-pre.1 (6000.4.0b11, 6000.5.0a8)

Tested on (OS): Windows 11