fix(color): extra sliders and trims on main view after creating a new model.

[philmoz]

Fixes an issue where, after creating a new model, two copies of the first model screen are added to the main view.

Can be reproduced by:

• select a model with all trims and sliders showing on main view
• create a new model using the 'Wing' wizard.
• note the duplicated trim/slider widgets on the main view.

[philmoz]

Affects 2.10 and 2.11.