I would propose that we perform two actions to more clearly demonstrate the dependencies of the ComboBox's properties:

1) Disabling the "Text" field when "Editable" is disabled.
Technically when it is disabled, nor the developer, nor the user should have the ability to edit this 'Text' content.

2) Re-Ordering the Properties to better reflect the order of operations for a Designer to:
-Placeholder (the most immediately visible aspect of this element's content, and in a lot of ways, somewhat serves as the "Content" field of other elements)
-Editable (required to 'unlock' the two following options)
-Text
-Stay Open on Edit
-Items Source
-{Advanced}