Clover uses "platform:/" URIs to load standard Eclipse icons from eclipse-core such as a package icon, a folder icon etc.

Eclipse Mars is buggy and does not always fetch these resources, as a consequence we don't see proper icons on a toolbar.

Fix: bundle new icons in Clover-for-Eclipse plugin and replace "platform:/" references by new icons using local URIs.

Note: try aligning look of new icons with ADG and Clover's HTML reports.