If interested, here's some details on how the DPI influences the application.
- Zoom / DPI Range
- 0.75 <=80
- 0.85 81-87
- 0.9 88-94
- 1.0 95-101 Default value on fresh install is 96.
- 1.1 102-108
- 1.2 109-115
- 1.3 116-122
- 1.4 123-129
- 1.5 >=130
The zoom levels are intended to match the size of the font used by other applications on the system.
As previously mentioned, Welcome only checks when it starts, it's not dynamic. You can also test them easily at the terminal:
ubuntu-mate-welcome --font-dpi=96