I think documentation of DefaultValue for e.g. DoubleUpDown is missleading, or at least I expected it to be another function set (using 3.3) but didn't see any issue that matched.

Documentation:
DefaultValue | Gets or sets the value to use when the Value is null and an increment/decrement operation is performed. (Inherited from U

To make typography legible on top of imagery, apply text protection in the form of scrims. Scrims are lightweight, translucent material layers.

Text protection from https://material.io/guidelines/style/imagery.html#imagery-best-practices

Notice that the selected text in the ComboBox2 is shorter when it is selected:

And when it is not, it the as expected

Notes:

• This is the Professional - System theme,

Do Not wrap the crappy default Folder browser..
Revamp the file-Save and make it work as a folder browser..

See the following..
http://www.lyquidity.com/devblog/?p=136

More examples of using the ModernUI Controls and examples that utilize a few controls in one application - also demonstrate best practices as how to use the controls and libraries effectively.