You can not adjust anything theming related inside SCSS files in the sencha/sass folder as the CSS for the theming has already been build.

All dependencies added to the dependencies entry inside the plugin's package.json file are considered to be provided by the app the plugin is added to. This means that (for now) a plugin cannot bring its own dependencies and can only utilize dependencies that are already part of the corresponding app.

While it is technically possible it is not intended that a plugin utilize a Blueprint dependency. This would lead to a cyclic dependency between the Blueprint workspace and the corresponding plugin (see Section, “Working with the Plugin Workspace”).